Fix wiki-links to use filename-based resolution

Quartz's "shortest" path mode resolves wiki-links by filename, not
frontmatter title. This fixes the broken links from the previous
title-based approach.

Changes:
- Rename zk duplicate files with -log suffix to avoid conflicts
- Rename reference/storage/postgresql.md to postgresql-storage.md
- Convert all wiki-links from [[Title]] to [[filename|Title]] format
- Rename doc-card-titles task to doc-filenames (checks filename uniqueness)
- Update pre-commit hook for renamed task

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/reference/storage/postgresql.md

@@ -1,10 +0,0 @@
----
-title: PostgreSQL Storage
-tags:
-  - storage
-  - database
----
-
-# PostgreSQL Storage
-
-See [[PostgreSQL]] in Services.