Feat 335 admin tools

[mohammadsherif0]

Summary

Adds an admin-only Admin Tools dashboard page (Settings nav) with a first tool to replace an existing document’s PDF or ZIP file on disk while keeping the same document id/hash. Intended for correcting a wrong submission file after the submission is closed.

New User Features

• Admin Tools page under Settings (admin_tools), admin-only nav entry
• Replace document file modal: type filter, search, paginated selectable table (10/page), upload replacement file
• Tool modal mounts only while open (lazy v-if) so document subscription is not loaded until needed

New Dev Features

• nav_element migration for Admin Tools (component: AdminTools, path admin_tools)
• Socket documentReplaceFile (admin-gated, transactional): validates PDF/ZIP type match, for PDFs clears CARE annotations/comments and best-effort strips embedded PDF annotations via PDFRPC, then overwrites files/{hash}.{pdf|zip}

Known Limitations

• If PDFRPC strip fails, the raw uploaded PDF is written instead
• No “import annotations from replacement PDF” option

Future Steps / open questions for review

• Clearing old CARE annotations: Keep always wiping CARE annotations/comments on PDF replace, or make it optional?
• Optional later: import-annotations checkbox on replace similar to upload Document
• Optional later: server-side document paging for very large admin document lists