feat(frontend): add Front/ — Vite/React frontend with backend pipeline integration

Mirror of design_agent_front/design-agent/ for shipping alongside backend.

Vite plugin (vitePluginPhaseZApi) endpoints :
  - POST /api/run   — spawn `python -m src.phase_z2_pipeline` with overrides
  - GET  /api/sample-mdx?mdx=03/04/05 — fixed sample MDX
  - GET  /frame-preview/{n} — figma preview thumbnails
  - GET  /data/runs/{run_id}/{path} — pipeline artifacts (final.html, step*.json, ...)

Env toggle forward (보고용) :
  PHASE_Z_ALLOW_RESTRUCTURE / PHASE_Z_ALLOW_REJECT / PHASE_Z_MAX_RANK=32

Components :
  - LeftMdxPanel (03/04/05 fix list + section tree)
  - SlideCanvas (iframe + slideOverrideCss prop for inline CSS inject)
  - FramePanel (label priority + confidence sort)
  - LayoutPanel

README with mermaid diagrams covering the 5-step demo flow.
node_modules / dist / .manus-logs / .env excluded via .gitignore.

Front/tsconfig.json

@@ -0,0 +1,23 @@
+{
+  "include": ["client/src/**/*", "shared/**/*", "server/**/*"],
+  "exclude": ["node_modules", "build", "dist", "**/*.test.ts"],
+  "compilerOptions": {
+    "incremental": true,
+    "tsBuildInfoFile": "./node_modules/typescript/tsbuildinfo",
+    "noEmit": true,
+    "module": "ESNext",
+    "strict": true,
+    "lib": ["esnext", "dom", "dom.iterable"],
+    "jsx": "preserve",
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "allowImportingTsExtensions": true,
+    "moduleResolution": "bundler",
+    "baseUrl": ".",
+    "types": ["node", "vite/client"],
+    "paths": {
+      "@/*": ["./client/src/*"],
+      "@shared/*": ["./shared/*"]
+    }
+  }
+}