Step 8: Polish — lint, clock abstraction, e2e test.

- golangci-lint config with errcheck, govet, staticcheck, errorlint
- Fix all lint issues (unchecked error returns in cleanup paths, De Morgan)
- Inject jonboulle/clockwork into Garden for deterministic timestamps
- Add manifest.NewWithTime() for clock-aware initialization
- E2e lifecycle test: init → add → checkpoint → modify → status → restore → verify
- Update CLAUDE.md, PROJECT_PLAN.md, PROGRESS.md

Phase 1 (local) is now complete. All 9 CLI commands implemented and tested.

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

.golangci.yaml

@@ -0,0 +1,25 @@
+version: "2"
+
+linters:
+  enable:
+    - errcheck
+    - govet
+    - ineffassign
+    - unused
+    - errorlint
+    - staticcheck
+
+linters-settings:
+  errcheck:
+    check-type-assertions: true
+  govet:
+    disable:
+      - shadow
+
+issues:
+  max-issues-per-linter: 0
+  exclude-rules:
+    - path: _test\.go
+      linters:
+        - gosec
+        - errcheck