feat(agents): add AGENTS.md and CLAUDE.md with pre-commit rules

- Add AGENTS.md: require make test before every non-doc commit and
  document the npm vendor asset workflow
- Add CLAUDE.md: instruct agents to read AGENTS.md at conversation start
- Add npm-install dependency to test-e2e Makefile target

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

AGENTS.md

@@ -0,0 +1,13 @@
+# Agent Instructions
+
+## Pre-Commit Validation
+
+- You MUST run `make test` before every commit whenever the staged change includes at least one file that is not `.md` or `.rst`, unless explicitly instructed otherwise.
+- You MUST commit only after all tests pass.
+- You MUST NOT commit automatically without explicit confirmation from the user.
+
+## Vendor Assets
+
+- Browser vendor assets (Bootstrap, Font Awesome, etc.) are managed via npm.
+- Run `npm install` inside `app/` to populate `app/static/vendor/` before starting the dev server or running e2e tests.
+- Never commit `app/node_modules/` or `app/static/vendor/` — both are gitignored and generated at build time.

CLAUDE.md

@@ -0,0 +1,5 @@
+# CLAUDE.md
+
+## Startup
+
+You MUST read `AGENTS.md` and follow all instructions in it at the start of every conversation before doing anything else.

Makefile

@@ -145,7 +145,7 @@ security: install-dev test-security
 	$(PYTHON) -m pip_audit -r /tmp/portfolio-runtime-requirements.txt
 
 .PHONY: test-e2e
-test-e2e:
+test-e2e: npm-install
 	# Run Cypress end-to-end tests via act (stop portfolio container to free port first).
 	-docker stop portfolio 2>/dev/null || true
 	$(ACT) workflow_dispatch -W .github/workflows/tests.yml -j e2e