fix: storyboard-angle review follow-ups (M1 bg-on-clip, B3 slideshow, parser guard, CLI fixes) (#1791)

* fix(skills): storyboard review — bg-on-clip rule, slideshow output, parser parity guard

Addresses the storyboard-angle review (jrusso1020):

- M1 (invisible text): frame-worker.md (x3) + SKILL.md Step 5 (x3) now require a
  frame's full-bleed background on a class=clip layer, never the #root /
  data-composition-id element (the root is clip-gated to its scene window, so a
  background on it is not a dependable ground and dark text can land on the black
  host body). The assembler already paints frame.md's canvas onto index #root as
  the base ground; the per-frame clip rides on top.
- B3 (slideshow truncates to slide 1): slideshow/SKILL.md gains an Output section
  (decks render via 'present'; 'render index.html' captures only the first
  composition; linear main-line MP4 export is deferred).
- Parser drift: vendoredParity.test.ts guards the three vendored storyboard.mjs
  copies (byte-identical + parse-parity with @hyperframes/core).
- skills-manifest.json regenerated for the edited SKILL.md files.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(cli): storyboard review — lint, validate help, snapshot, inspect, capture, render

Addresses the CLI findings from the storyboard-angle review (jrusso1020):

- lint (@hyperframes/lint): accept vendor-prefixed system-font keywords
  -apple-system / BlinkMacSystemFont so a system stack with a generic fallback no
  longer trips font_family_without_font_face (+ test).
- help: list 'validate' under Project in 'hyperframes --help' (was runnable but
  undocumented).
- snapshot: honor -o/--output (the flag did not exist; output was hardcoded to
  snapshots/). The dir is resolved once and threaded through capture + contact
  sheet + Gemini.
- snapshot: split font status into loaded / error / unused with a one-line
  summary; only a real 'error' is reported as FAILED (an unrequested @font-face
  is 'unused', not a contradiction with 'loaded').
- inspect: suppress text_occluded across a scene-to-scene crossfade (occluder in
  a different data-composition-id mount while a scene is mid-fade); a same-scene
  or two-settled-scenes overlap still flags.
- inspect: suppress content_overlap between in-flow siblings governed by the same
  flex/grid container (tight stacks / number lockups are layout slop).
- capture: record source resolution (videoWidth/Height) in video-manifest.json
  alongside the DOM display box; consumers size off the source dims.
- render: warn when the target carries a slideshow island (render captures only
  the first scene, so the MP4 is truncated to slide 1; use 'present').

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

skills/faceless-explainer/SKILL.md

@@ -128,6 +128,8 @@ Before dispatch, read `sub-agents/frame-worker.md` and `../hyperframes-core/refe
 
 Each worker context must include `PROJECT_DIR`, `frame_id`, canvas size, caption status and keep-out band if captions are enabled, and `RULES_DIR` as the absolute path to this skill's `../hyperframes-animation/rules/`. Each worker reads `frame.md`, its own `## Frame N` block from `STORYBOARD.md`, the local rule recipe (`../hyperframes-animation/rules/<id>.md`) for each cited motion, and the frame's blueprint template (`../hyperframes-animation/blueprints/<id>.md`). Each worker writes only `compositions/frames/NN-*.html`. Workers must never edit `STORYBOARD.md`.
 
+**Full-bleed backgrounds ride on a `class="clip"` layer, never the `#root`.** A frame's ground (color field / gradient / grid) is its own full-duration background clip — a `background` set on the `#root` / `data-composition-id` element is clip-gated to the frame's window and is not a dependable ground, so dark content can land on the black host `body` and render invisible. The video's base ground is painted by the assembler from `frame.md`'s `canvas` color onto the index `#root`. (Full rule + self-check: `sub-agents/frame-worker.md`.)
+
 As each worker returns, the orchestrator marks that frame as `animated` in `STORYBOARD.md`.
 
 After audio timings exist, build captions in the background and assemble the index: