feat: root validate chains CLI/TUI/launcher build + test (#1485) (#1495)

Root `npm run validate` previously delegated only to `clients/web`
(`format:check` + `lint` + `build` + `test:coverage`), so a contributor
running it before pushing could miss CLI/TUI/launcher breakage that CI
would later catch. There was no single local command mirroring CI.

Extend root `validate` to mirror the CI job end to end:
- `validate:web` — web format:check + lint + build + test:coverage
- `test:cli` / `test:tui` — CLI and TUI suites
- `validate:launcher` — build CLI + TUI + launcher, then the launcher
  `--help` smoke (`smoke:launcher`: --help, --cli --help, --tui --help)

The new sub-scripts can be run individually when iterating on one
client. Storybook stays out of `validate` (Playwright-dependent, slow),
consistent with the existing convention. Documented in AGENTS.md.

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

package.json

@@ -37,7 +37,10 @@
     "prepack": "npm run build",
     "test:cli": "cd clients/cli && npm run test",
     "test:tui": "cd clients/tui && npm run test",
-    "validate": "cd ./clients/web/ && npm run validate",
+    "validate": "npm run validate:web && npm run test:cli && npm run test:tui && npm run validate:launcher",
+    "validate:web": "cd clients/web && npm run validate",
+    "validate:launcher": "npm run build:cli && npm run build:tui && npm run build:launcher && npm run smoke:launcher",
+    "smoke:launcher": "node clients/launcher/build/index.js --help && node clients/launcher/build/index.js --cli --help && node clients/launcher/build/index.js --tui --help",
     "test": "cd ./clients/web/ && npm run test && cd ../cli && npm run test && cd ../tui && npm run test",
     "test:coverage": "cd ./clients/web/ && npm run test:coverage",
     "test:storybook": "cd ./clients/web/ && npm run test:storybook",