♻️ refactor(import-follow): deduplicate cleanup/audit hygiene option layer

- Extract shared followImportsHygieneOptions struct for common paths,
  filters, retention profiles, fail-if-matched, and age-gating
- Unify flag parsing, retention-profile application, and validation
  for both cleanup-follow-imports and audit-follow-imports commands
- Add audit-side tests for invalid pattern and retention-profile parsing
- Rename follow_examples_test.go to follow_import_example_fixtures_test.go

Author: cocosip

docs/go/maintainer/development-tracker.md

@@ -151,7 +151,14 @@ Immediate next tasks:
 
 ### 2026-03-17 Session Update
 
-- Completed: Removed the maintainer-only `--list-examples` / `--refresh-examples` execution path from the production `cleanup-follow-imports` and `audit-follow-imports` commands. Hygiene example catalogs now live only in `internal/app/follow_examples_test.go`, checked-in fixture rewrites happen through env-gated test helpers, and the operator/maintainer docs now describe that test-driven maintenance flow instead of advertising unsupported runtime flags.
+- Completed: Deduplicated the shared cleanup/audit hygiene option layer in `internal/app/import_follow.go`. `cleanup-follow-imports` and `audit-follow-imports` now embed one common option struct for shared paths, filters, retention profiles, fail-if-matched, and age-gating; they reuse the same common flag parser, retention-profile application, and pattern/age/target-binding validation while keeping command-specific prune/check flags separate. App tests now also cover audit-side invalid pattern and retention-profile parsing so both command families stay aligned under one helper path.
+- In progress: none.
+- Blockers: none.
+- Next step: pivot from this follow/import parser cleanup back to a new operator-facing capability, unless another small cleanup slice around report/renderer sharing is clearly higher value.
+
+### 2026-03-17 Session Update
+
+- Completed: Removed the maintainer-only `--list-examples` / `--refresh-examples` execution path from the production `cleanup-follow-imports` and `audit-follow-imports` commands. Hygiene example catalogs now live only in `internal/app/follow_import_example_fixtures_test.go`, checked-in fixture rewrites happen through env-gated test helpers, and the operator/maintainer docs now describe that test-driven maintenance flow instead of advertising unsupported runtime flags.
 - In progress: none.
 - Blockers: none.
 - Next step: decide whether the remaining cleanup/audit flag parsing should also move behind a smaller shared helper, or whether the next slice should return to a new operator-facing capability.

docs/go/maintainer/mcp-integration.md

@@ -251,7 +251,7 @@ go test ./internal/app -run TestRefreshAuditFollowImportsExampleFixtures
 Remove-Item Env:CODEX_MEM_REFRESH_AUDIT_EXAMPLES
 ```
 
-If you only need a subset while iterating, pass the exact fixture names through the matching environment variable. The canonical names live in [../../../internal/app/follow_examples_test.go](../../../internal/app/follow_examples_test.go):
+If you only need a subset while iterating, pass the exact fixture names through the matching environment variable. The canonical names live in [../../../internal/app/follow_import_example_fixtures_test.go](../../../internal/app/follow_import_example_fixtures_test.go):
 
 ```powershell
 $env:CODEX_MEM_REFRESH_CLEANUP_EXAMPLES = "filtered-cleanup-json"

docs/go/operator/import-ingestion.md

@@ -297,7 +297,7 @@ go test ./internal/app -run TestRefreshAuditFollowImportsExampleFixtures
 Remove-Item Env:CODEX_MEM_REFRESH_AUDIT_EXAMPLES
 ```
 
-The fixture names live in [follow_examples_test.go](../../../internal/app/follow_examples_test.go), and the ordinary read-only guard remains:
+The fixture names live in [follow_import_example_fixtures_test.go](../../../internal/app/follow_import_example_fixtures_test.go), and the ordinary read-only guard remains:
 
 ```powershell
 go test ./internal/app -run "Test(Audit|Cleanup)FollowImportsExampleOutputsStayInSync"