fix(studio): SSR-safe player load, captions import cleanup (#248)

* fix(studio): load @hyperframes/player lazily to support SSR

Player.tsx had a bare `import "@hyperframes/player"` at module scope. The
player package registers a class that extends HTMLElement as a side effect,
and HTMLElement doesn't exist in a Node server runtime. Any consumer that
imported from @hyperframes/studio during server-side rendering (e.g. the
Next.js App Router evaluating a client component for SSR) threw
`HTMLElement is not defined`.

Move the import inside the mount effect via dynamic `import(...)` so it
only runs in the browser, and wire up a cancellation flag and deferred
cleanup so a fast unmount doesn't leak listeners or DOM nodes.

* fix(studio): remove .js extensions from captions-internal imports

The captions module imported sibling files as `./types.js` and
`./parser.js`. That's legal ESM TypeScript, but Turbopack (and other
bundlers) refuse to resolve those specifiers against .ts files when the
package is consumed from node_modules — the rest of @hyperframes/studio
uses extensionless imports for that reason.

Align captions with the rest of the codebase so the package builds
without bundler-specific configuration in consumers.

* chore: release @hyperframes/player@0.2.7 and @hyperframes/studio@0.2.9

Ships the root-timeline resolution fix (#247), the SSR-safe player load,
and the captions import cleanup.

packages/player/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@hyperframes/player",
-  "version": "0.2.6",
+  "version": "0.2.7",
   "description": "Embeddable web component for HyperFrames compositions",
   "repository": {
     "type": "git",