feat(sdk): expose Project.getCanvasLayout and full ScreenData metadata (#365, #138) (3 of 3)

[davideast]

Summary (PR 3 of 3 — Tier 3 Issues #365 & #138)

Stacks on #378 (fix/issue-361-edit-screen-freshness).

1. Resolves feat: Add canvas layout sync API for screenInstances (position, label, add/remove) #365 (get_project binding & Project.getCanvasLayout()):
   • Binds the get_project MCP tool to Project.get() in domain-map.json to hydrate full ProjectData (including screenInstances and designTheme).
   • Adds Project.prototype.getCanvasLayout() (packages/sdk/src/project-ext.ts + packages/sdk/src/spec/canvas.ts) which returns normalized CanvasScreenInstance[] items with extracted screenId, canvas coordinates (x, y), dimensions (width, height), deviceType, label, and hidden state.
2. Resolves get_screen returns incomplete screen data — missing theme, designMd, screenMetadata #138 (Complete ScreenData schema & getters on Screen):
   • Expands ScreenData in scripts/generate-sdk.ts to include width, height, deviceType, screenType, generatedBy, prompt, theme, designSystem, and screenMetadata, and generates typed getters on Screen (screen.width, screen.height, screen.deviceType, screen.screenType, screen.screenMetadata).

Verification

• Added packages/sdk/test/unit/issue-365-138-canvas-and-metadata.test.ts (RED -> GREEN).
• Added Project.get fixture to packages/sdk/test/unit/response-fixtures.test.ts.
• Verified bun run generate, bun run typecheck, bun run validate:generated, bun run test:scripts, bun run check:skills, and bun run test:coverage (45 test files, 368 tests passing).

Closes #365
Closes #138