chore: add one-click setup/start/stop scripts, migration CLI, and seed tool

- Add idempotent seed tool with duplicate detection for agents/issues/comments
- Add migration CLI supporting up/down with schema_migrations tracking
- Add Makefile targets: make setup (first-time), make start, make stop
- Update .gitignore for test artifacts and compiled binaries

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

.gitignore

@@ -21,6 +21,11 @@ coverage
 # Go
 server/bin/
 server/tmp/
+server/migrate
+
+# Test artifacts
+test-results/
+apps/web/test-results/
 
 # context (agent workspace)
 .context