feat: port CLI, TUI, and launcher from v1.5 into v2 (#1452)

Ports the CLI, TUI, and launcher from v1.5 into v2 behind a single
`mcp-inspector` entrypoint (launcher → web/cli/tui). Includes the
`mcp-inspector --web --dev` launcher fix (Vite alias resolution + prod-server
double-start), the root `postinstall` install cascade with simplified CI, and
spec/AGENTS docs (no-workspaces rationale, Development setup).

Closes #1246.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/main.yml

@@ -16,11 +16,10 @@ jobs:
           node-version: '20.x'
           cache: 'npm'
 
-      - name: Install root dependencies
-        run: npm install
-
-      - name: Install web client dependencies
-        working-directory: ./clients/web
+      - name: Install dependencies (root + all clients)
+        # The root postinstall (scripts/install-clients.mjs) cascades
+        # `npm install` into clients/web, clients/cli, clients/tui, and
+        # clients/launcher, so this single step sets up every client.
         run: npm install
 
       - name: Check formatting
@@ -39,6 +38,23 @@ jobs:
         working-directory: ./clients/web
         run: npm run test:coverage
 
+      - name: Run CLI tests
+        working-directory: ./clients/cli
+        run: npm run test
+
+      - name: Run TUI tests
+        working-directory: ./clients/tui
+        run: npm run test
+
+      - name: Build CLI, TUI, and launcher
+        run: npm run build:cli && npm run build:tui && npm run build:launcher
+
+      - name: Smoke test launcher
+        run: |
+          node clients/launcher/build/index.js --help
+          node clients/launcher/build/index.js --cli --help
+          node clients/launcher/build/index.js --tui --help
+
       - name: Cache Playwright browsers
         uses: actions/cache@v4
         with: