refactor(core): extract shared studio API module (#113)

## Summary
Extracts all studio API routes into a shared Hono-based module at `@hyperframes/core/studio-api`.

### Architecture
- **`StudioApiAdapter` interface** — consumers inject host-specific behavior (project resolution, bundling, rendering, thumbnails)
- **Shared route modules**: projects, files, preview, lint, render, thumbnail
- **Shared helpers**: `isSafePath`, `walkDir`, `getMimeType`, `buildSubCompositionHtml`

### What this PR does
- Creates the shared module with all API routes extracted from both `vite.config.ts` and `studioServer.ts`
- Both consumers will be refactored in follow-up commits to mount this module with their own adapter

### What stays in each consumer
- **Vite**: SSR module loading, Puppeteer thumbnails, file watcher + HMR, producer HTTP proxy, multi-project scanning
- **CLI**: in-process `executeRenderJob`, local runtime serving, browser management, SPA static file serving

### Follow-up needed
- [ ] Refactor `packages/studio/vite.config.ts` to use `createStudioApi(adapter)` via `@hono/node-server`'s `getRequestListener`
- [ ] Refactor `packages/cli/src/server/studioServer.ts` to use `createStudioApi(adapter)`
- [ ] Add `./studio-api` export path to `packages/core/package.json`
- [ ] Add `hono` as peer dependency of `@hyperframes/core`

## Test plan
- [ ] Verify shared module compiles without type errors
- [ ] After consumer refactoring: all studio features work identically via both vite dev and CLI embedded servers

🤖 Generated with [Claude Code](https://claude.com/claude-code)

packages/core/package.json

@@ -28,7 +28,11 @@
       "import": "./src/compiler/index.ts",
       "types": "./src/compiler/index.ts"
     },
-    "./runtime": "./dist/hyperframe.runtime.iife.js"
+    "./runtime": "./dist/hyperframe.runtime.iife.js",
+    "./studio-api": {
+      "import": "./src/studio-api/index.ts",
+      "types": "./src/studio-api/index.ts"
+    }
   },
   "publishConfig": {
     "access": "public",
@@ -45,7 +49,11 @@
         "import": "./dist/compiler/index.js",
         "types": "./dist/compiler/index.d.ts"
       },
-      "./runtime": "./dist/hyperframe.runtime.iife.js"
+      "./runtime": "./dist/hyperframe.runtime.iife.js",
+      "./studio-api": {
+        "import": "./dist/studio-api/index.js",
+        "types": "./dist/studio-api/index.d.ts"
+      }
     },
     "main": "./dist/index.js",
     "types": "./dist/index.d.ts"
@@ -81,6 +89,14 @@
     "typescript": "^5.0.0",
     "vitest": "^3.2.4"
   },
+  "peerDependencies": {
+    "hono": "^4.0.0"
+  },
+  "peerDependenciesMeta": {
+    "hono": {
+      "optional": true
+    }
+  },
   "optionalDependencies": {
     "cheerio": "^1.2.0",
     "esbuild": "^0.25.12"