Reduce pre-commit context noise, gitignore agent artifacts

Slim Vitest pre-commit output with dot reporter and coverage summary.
Ignore .agent-tests/ and docs/agents/research/ in git.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -12,4 +12,6 @@ Thumbs.db
 coverage/
 *.tsbuildinfo
 docs/agents/plans/
+docs/agents/research/
+.agent-tests/
 .rodney/

lefthook.yml

@@ -26,4 +26,4 @@ pre-commit:
           - name: oxlint
             run: pnpm oxlint -- --deny warnings
           - name: test
-            run: pnpm test
+            run: pnpm vitest run --reporter=dot --coverage.reporter=text-summary