fix(organizer): reconcile filename mode symlinks

[samtruman]

Summary

When ORGANIZER_FILENAME_MODE changes between canonical and original release filenames, existing organized symlinks were left behind. In deployments where the same source is visible through different mount aliases, source identity could also be misclassified.

This follow-up makes filename-mode changes converge safely:

• compares source identity using normalized paths and realpath when available;
• tracks the desired organized target for each source during an organizer run;
• removes only obsolete organized symlinks that point to the same provider source;
• removes empty directories left by those obsolete links;
• preserves regular files and distinct media versions.

This is generic organizer behavior and does not depend on any deployment-specific paths, compose files, or provider configuration.

Validation

• Targeted organizer filename tests: pass (6 tests)
• Typecheck: pass
• Full pre-commit test suite: pass (149 tests, 0 failures)
• git diff --check: pass

Related to the filename-mode behavior introduced by #125.

[moderniselife]

Thanks @samtruman, this looks good to me. Comparing sources by realpath fixes the duplicate-link case for mount aliases, and the reconcile pass is nicely conservative: it only unlinks symlinks (never real files), skips dry runs, and only removes a link when the same source has a different desired target. CI is green; I've queued it for a final merge decision.

[samtruman]

Thanks for the review. I reproduced a separate runtime issue on provider-backed FUSE mounts: realpath() can block organizer startup/reconciliation when the remote is degraded. The focused correction is available in PR #136, which avoids realpath() for paths under the configured provider mount while preserving local-filesystem alias handling. PR #133 remains closed and is superseded by #136.