feat(skills): mode-first briefs, value-first storyboards, and destination defaults across creation workflows (#2058)

* feat(skills): add brief contract — interaction modes + shared intake fields across workflows

New hyperframes-core/references/brief-contract.md, the shared intake
contract every creation workflow now runs its brief against:

- §1 interaction mode: collaborative (default) vs autonomous, ongoing
  vs one-time signals, mode set once and carried forward, and a gate
  taxonomy (preference / checkpoint / quality / routing) — autonomous
  skips waiting, never verification
- §2 field registry: destination→aspect derivation (feed → 1:1,
  Shorts/TikTok → 9:16, else 16:9), message, angle, length, audience,
  language, narration — each workflow binds fields as ask or state
- §3 question rules: one round with one question per asked field
  (native question UI mandatory when available, recommended option
  first with a receipt), never drop a question as inferable, and a
  mode legend advertised in the intro text instead of asked

Wired into the surfaces:

- hyperframes router: detect mode at entry, derive aspect from
  destination instead of stating 16:9
- product-launch-video / pr-to-video / faceless-explainer: ask/state
  binding tables at Step 0; Step 3/6 checkpoint-gate branches
  (autonomous posts a heads-up with a preview hint before render)
- website-to-video: local mode definition now defers to the contract
- music-to-video, general-video, embedded-captions, talking-head-recut,
  slideshow, motion-graphics: mode semantics wired per gate type
- storyboard-format: new optional 'mode' frontmatter key
- pr-to-video: length tier is a ceiling, not a floor — a one-headline
  PR recommends inside the 30–90s sweet spot regardless of diff size

* feat(skills): story spine + mode-first brief across creation workflows

Story — the reverse-iceberg feedback:

- New hyperframes-creative/references/story-spine.md, three rules for
  the narrated workflows: the hook speaks the viewer's outcome
  language, the value claim lands by beat 2 (implementation is the
  footnote of the story, not the spine), and the storyboard is
  presented as a proposal — 'This video tells [audience] that
  [message]' plus a per-frame why: drawn from narrativeRole
- pr-to-video: feature-reveal reordered promise-first (impact leads,
  diff/mechanism follow as evidence); hooks ban file/function names;
  fix-explainer, refactor-walkthrough, changelog unchanged
- product-launch-video / faceless-explainer hook rules aligned to the
  spine; website-to-video's beat summary gains the echo line + why:;
  general-video points at the spine from its plan step

Brief — hardened after live-test drift:

- Mode is now the first question (Collaborative recommended vs
  Autonomous), its own round, skipped when the request carries a
  signal; autonomous asks nothing further until one final
  preview-or-render question before render
- Step 0 rewritten as a literal two-round question script in each
  shot-sequence workflow (website-to-video's editorial register,
  channel-agnostic); brief-contract.md §3 reduced to invariants so the
  procedure lives in exactly one place

* feat(skills): split type minimums by viewing context

typography.md: full-screen viewing keeps body 20px / headline 60px;
in-feed destinations (X / LinkedIn / Instagram — brief-contract's
destination field) scale to body >=32px, headline >=90px, data labels
>=24px. First-pass values, to be calibrated against real renders.

* feat(skills): storyboard proposal as a table + credits close by default

- story-spine § 3: the proposal presents frames as a markdown table
  (frame · beat · on screen · why) instead of dense paragraphs; the
  three shot-sequence workflows and website-to-video's beat summary
  reference the same shape
- pr-to-video: the credits close is now the default ending — every PR
  video ends on a contributors frame (committers by commit count, 1-6
  avatars), with no taste judgment; the only skip is when no avatar
  was fetched, and the user can cut the frame in the proposal

* fix(skills): address review nits on the brief/story contracts

- embedded-captions: the identity procedure now states both sides of the
  preference gate inline (user picks; autonomous picks with a stated why)
- website-to-video step-2-brief: note that its mode section is the
  workflow's application of brief-contract.md, not a second definition
- brief-contract: resuming a project reads mode from STORYBOARD.md
  frontmatter — a recorded mode counts as set, closing the write-only gap

* docs(skills): add a non-code receipts example to the brief contract

Review nit (jrusso1020, #2058): the receipts example in § 3 was
PR-video-shaped only. A destination-shaped example joins it so the rule
reads as workflow-neutral.

skills/website-to-video/references/step-2-brief.md

@@ -118,7 +118,7 @@ When the user gives no creative direction, default to what the brand's visual id
 
 With that minimum in hand, still write an ambitious storyboard. "Surprise me" means "impress me," not "play it safe." Go bold.
 
-**Autonomous mode propagates — for user-preference gates only.** When the user signals "surprise me" / "decide for me" / "just build it" here at Step 2, that signal kills downstream user-preference 💬 gates: Step 3's storyboard approval, Step 4's TTS provider choice, music yes/no, captions yes/no. Make those creative decisions yourself and present the finished video at the end. Do not ask four separate questions across four separate steps. Read the room once and commit.
+**Autonomous mode propagates — for user-preference gates only.** (Mode semantics — signals, propagation, gate types — are canonical in `../../hyperframes-core/references/brief-contract.md`; this section is this workflow's application of them, not a second definition.) When the user signals "surprise me" / "decide for me" / "just build it" here at Step 2, that signal kills downstream user-preference 💬 gates: Step 3's storyboard approval, Step 4's TTS provider choice, music yes/no, captions yes/no. Make those creative decisions yourself and present the finished video at the end. Do not ask four separate questions across four separate steps. Read the room once and commit.
 
 **Auto mode does NOT skip quality-verification gates.** These run regardless and must produce evidence in your final summary:
 

skills/website-to-video/references/step-3-storyboard.md

@@ -542,15 +542,17 @@ After writing the storyboard AND the script, present BOTH to the user for review
 
 ### How to Present
 
-Summarize the plan clearly. Don't dump the full STORYBOARD.md — give the user a beat-by-beat overview they can scan in 30 seconds:
+Summarize the plan clearly. Don't dump the full STORYBOARD.md — give the user a beat-by-beat overview they can scan in 30 seconds. Per `../../hyperframes-creative/references/story-spine.md` § 3, the summary is a proposal: open by echoing the strategy line, and give every beat a `why:` traced to the message:
 
-> **Here's what I've planned for your [duration] [type]:**
+> **This video tells [audience] that [message].** Here's the plan for your [duration] [type]:
 >
-> **Beat 1 (0:00–0:04):** [one sentence — what happens visually + what the narration says]
-> **Beat 2 (0:04–0:10):** [one sentence]
-> **Beat 3 (0:10–0:18):** [one sentence] _(hero beat — 3D MacBook reveal with bloom effect)_
-> ...
-> **Beat N (closing):** [one sentence — CTA/logo]
+> | Beat          | On screen + narration                                              | Why                                     |
+> | ------------- | ------------------------------------------------------------------ | --------------------------------------- |
+> | 1 (0:00–0:04) | [one sentence — what happens visually + what the narration says]   | [the beat's job, traced to the message] |
+> | 2 (0:04–0:10) | [one sentence]                                                     | […]                                     |
+> | 3 (0:10–0:18) | [one sentence] _(hero beat — 3D MacBook reveal with bloom effect)_ | […]                                     |
+> | …             | …                                                                  | …                                       |
+> | N (closing)   | [one sentence — CTA/logo]                                          | […]                                     |
 >
 > **Style:** [dimension summary — e.g., "Cinematic pacing, dark mood, dramatic transitions for hero, clean for the rest"]
 > **Narration:** [first and last line of the script]