Add app.ps1 dev lifecycle script (start/stop/restart/rebuild/status/logs)

A single PowerShell entry point for the local stack:
- refreshes PATH from the registry so it works in stale terminals
- ensures PostgreSQL is up; starts the Go API and Angular dev server
- tracks PIDs in .run/ and also sweeps the ports on stop
- rebuild (-Clean/-Install), status and logs (-Follow) actions

.run/ (pids, logs) is git-ignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -35,3 +35,6 @@ backend/coverage.out
 frontend/coverage/
 e2e/evidence-report/
 e2e/**/*.pdf
+
+# --- app.ps1 runtime (pids, logs) -------------------------------------------
+.run/