feat(core): add registry schema + TS types (#252)

* feat(core): add registry schema + TS types

PR 1/17 of the catalog system rollout. Foundation for a shadcn-style
registry with three item tiers: examples (full projects), blocks
(sub-compositions), components (effect snippets).

## What

- TS types: RegistryItem (discriminated union of ExampleItem/BlockItem/
  ComponentItem), RegistryManifest, FileTarget, ItemType, FileType
- JSON Schemas: schemas/registry.json, schemas/registry-item.json
- Compile-time exhaustiveness asserts on ITEM_TYPES/FILE_TYPES so adding
  to the TS union without updating the constant stops compiling
- Drift-guard test: schema enums must equal ITEM_TYPES/FILE_TYPES by
  set-equality; exactly 2 distinct type enums in registry-item.json
- Public API via new ./registry export path plus re-exports from root;
  schemas exposed via ./schemas/registry.json export for external tooling

## Why

- Every downstream PR (resolver, installer, hyperframes add, docs
  codegen, CI previews, skill, catalog command) builds on these types
- Getting the shape right now avoids painful migrations later

## How

- Discriminated union enforces that components do not have dimensions
  or duration and examples/blocks must have them (schema mirrors via
  if/then/else on the type discriminant)
- target path pattern rejects .. segments, Unix absolute paths, and
  Windows drive letters (defense-in-depth; CLI validates at runtime in
  PR 3)
- name pattern requires alphanumeric start and end (no trailing hyphens)
- Optional metadata: version, author, license, deprecated, minCliVersion
- additionalProperties: false on nested objects (catches typos on
  critical fields) but relaxed on top-level RegistryItem (allows
  third-party custom metadata in PR 15 custom registries)

## Test plan

- [x] Unit tests: 11 new tests covering type guards, discriminant
      narrowing, schema/TS drift guards, schema \$id sanity, optional
      metadata acceptance, and compile-time checks (via @ts-expect-error)
- [x] bun run test in packages/core: 445 passed (was 434 on main,
      +11 from this PR)
- [x] bunx oxfmt and bunx oxlint: clean
- [x] bun run typecheck: clean
- [ ] Manual testing: N/A (types + schemas only)
- [ ] Documentation updated: per-item doc pages land in PR 9 (codegen
      from these manifests); guide updates in PR 10+

## Breaking / migration

None. Pure additive — new module, new export paths, no existing
surface touched.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(core): remove version field + hyperframes:demo file type

Address review feedback from Miguel:

- Remove `version` from RegistryItemBase + schema. Per shadcn model,
  the registry is versioned by git tags, not per-item. The adversarial
  review added it; the original design doc was correct.
- Remove `hyperframes:demo` from FileType union + FILE_TYPES constant
  + schema. Demo files exist on disk for the CI preview pipeline but
  are NOT installed to user projects and should not appear in
  registry-item.json files[]. Neither shadcn nor Remotion has a
  dedicated demo file type — demos are just compositions.
- Add `required: ["type"]` to the if-condition in the schema's
  allOf discriminant (Miguel's nit — makes the condition self-
  contained)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(ci): add shader-transitions to Dockerfile.test

PR #251 added packages/shader-transitions/ to the workspace but didn't
update Dockerfile.test to COPY its package.json. This caused
`bun install --frozen-lockfile` to fail in the regression Docker build:
bun saw a lockfile referencing @hyperframes/shader-transitions but the
package.json wasn't present in the container, so it wanted to remove
the entry — triggering "lockfile had changes."

Verified: Docker build passes with `--no-cache` after this fix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/core/src/index.ts

@@ -163,3 +163,26 @@ export { createGSAPFrameAdapter } from "./adapters/gsap";
 // Text measurement
 export { fitTextFontSize } from "./text/index.js";
 export type { FitTextOptions, FitTextResult } from "./text/index.js";
+
+// Registry
+export type {
+  ItemType,
+  FileType,
+  FileTarget,
+  RegistryItemDimensions,
+  RegistryItemPreview,
+  RegistryItem,
+  ExampleItem,
+  BlockItem,
+  ComponentItem,
+  RegistryManifestEntry,
+  RegistryManifest,
+} from "./registry/index.js";
+
+export {
+  ITEM_TYPES,
+  FILE_TYPES,
+  isExampleItem,
+  isBlockItem,
+  isComponentItem,
+} from "./registry/index.js";