chore(#25): add poe ci task to mirror GitHub Actions locally

- Add install-frontend task (npm ci)
- Make build-frontend auto-install deps before build
- Add poe ci task: lint + typecheck + test + build-frontend
- Document poe ci in CONTRIBUTING.md

Closes #25

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: etoyama

CONTRIBUTING.md

@@ -37,7 +37,8 @@ poe format          # Auto-fix lint issues and format
 poe typecheck       # Type check (ty)
 poe test            # Run tests (pytest)
 poe all             # Run lint + typecheck + test
-poe build-frontend  # Rebuild frontend assets
+poe build-frontend  # Install deps and build frontend assets
+poe ci              # Run the full CI pipeline locally (Python + frontend)
 ```
 
 ## Code Style

pyproject.toml

@@ -101,16 +101,24 @@ cmd = "uv run ty check src/"
 [tool.poe.tasks.test]
 cmd = "uv run pytest -v"
 
+[tool.poe.tasks.install-frontend]
+cmd = "npm --prefix frontend ci"
+help = "Install frontend dependencies"
+
 [tool.poe.tasks.build-frontend]
-cmd = "npm --prefix frontend run build"
-help = "Build frontend assets"
+sequence = ["install-frontend", {cmd = "npm --prefix frontend run build"}]
+help = "Install deps and build frontend assets"
 
 [tool.poe.tasks.build]
 sequence = ["build-frontend"]
 
 [tool.poe.tasks.all]
 sequence = ["lint", "typecheck", "test"]
 
+[tool.poe.tasks.ci]
+sequence = ["lint", "typecheck", "test", "build-frontend"]
+help = "Run the full CI pipeline locally (Python + frontend)"
+
 [dependency-groups]
 dev = [
     "httpx>=0.27",