fix: gemini-watcher re-entrancy guard + mtime-based change detection #146

Job	Run time
Secret Scan (gitleaks)	4s
Typecheck	22s
Lint	13s
Server Unit Tests	24s
Server DB Integration Tests	31s
Unit Tests (Node 20)	1m 49s
Web Tests	30s
Unit Tests (Node 22)	1m 51s
Repo Provider Integration Tests	19s
Coverage Report	2m 13s
E2E Tests	39s
Docker Build & Push	45s
Publish to npm	2m 25s
	12m 5s

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