docs: add the Studio section, workflow guides, and section hubs

Adds the pages the rebuilt navigation is organised around, and moves the sidebar
onto that structure. Every entry points at a file that exists after this commit;
nothing is rewritten or removed yet, and no redirect is claimed yet.

- Studio (13 pages) — the editor had no section of its own
- One guide per creation workflow, matching the shipped agent skills
- Section hubs: Concepts, Catalog, Developers, Deploy, Workflows, Help,
  Go further, Product updates, 30 Days of HyperFrames

Pages a later commit retires drop out of the sidebar here but still exist and
still resolve, so the site stays navigable at this commit.

Incidentally fixes a link to /concepts from the Lambda migration guide that is
broken on main today — the destination did not exist.

docs/guides/music-to-video.mdx

@@ -0,0 +1,68 @@
+---
+title: "Create a music-driven video"
+sidebarTitle: "Music video"
+description: "Cut footage, images, lyrics, and motion to a track’s beat grid."
+---
+
+import { DocsVideo } from "/snippets/docs-video.jsx";
+
+Start with a music file—or a video whose audio should control the edit. Narration is not added; the track is the spine.
+
+<Frame caption="A complete music-driven film. Its sections, visual treatments, and cuts follow the track.">
+  <DocsVideo
+    title="A complete music-driven film"
+    src="https://static.heygen.ai/hyperframes-oss/docs/images/showcase/full-music.mp4"
+    poster="https://static.heygen.ai/hyperframes-oss/docs/images/showcase/wfv2-music.jpg"
+  />
+</Frame>
+
+## Make the request
+
+Attach the track and any media that must appear:
+
+```text
+Using /hyperframes, turn assets/song.wav and the photos in assets/tour into a
+30-second music-driven video.
+```
+
+The agent analyzes the real track before planning the cut. Mention a required
+section, lyric, image order, or delivery format when it cannot be chosen freely.
+
+## What should the track drive?
+
+- **Use your photos or video** — cut approved media to the track's phrases, energy, beats, and ending.
+- **Make a lyric video** — verify the words first, then synchronize and design each line around the vocal.
+- **Invent the visuals** — build the visual arc from typography, graphic elements, and motion when no media is supplied.
+
+A complete video can also be built entirely from type, graphic templates, and
+motion.
+
+## The track sets the structure
+
+HyperFrames maps the track’s phrases, energy, onsets, silences, rolls, drops, and hard stops before it plans the visuals.
+
+A rhythmic track can support cuts on its real beat grid. Calm or loose music should flow by phrase and energy instead of forcing a cut onto every measured beat.
+
+The visual treatments change at meaningful musical moments. More beats do not automatically mean more scenes.
+
+## Review the rhythm
+
+- The correct section of the track is used.
+- Required media appears and lyrics match the vocal.
+- The strongest visual changes land on meaningful musical changes.
+- Important images and text remain long enough to understand.
+- The ending reaches a musical landing or forms a deliberate loop.
+
+For direct timing control, use the [Studio timeline](/studio/timeline) to refine
+cuts, holds, and the ending against the beat markers. Ask the agent when the
+section, media plan, or overall treatment must change.
+
+<Card title="Finish and share" icon="circle-check" href="/guides/export-and-share">
+  Check the final project, render through your preferred surface, and review the file.
+</Card>
+
+## Related topics
+
+- [Edit cuts and holds on the Studio timeline](/studio/timeline)
+- [Work with voice, music, sound, and captions](/guides/voice-and-audio)
+- [Prompt for music videos and slideshows](/prompting/music-and-slideshows)