feat(editor): detect image URLs on paste and display as image blocks

[j4rviscmd]

Summary

• Implement multi-stage image URL detection pipeline (extension check → known domain heuristic → async HEAD Content-Type check) to render pasted HTTPS image URLs as image blocks instead of plain links
• Add 3-tier naming strategy for image blocks: page title → filename without extension → "image"
• Fix RenameDialog focus management by moving it outside BlockNoteView
• Add read-only path row with copy button to RenameDialog
• Strip extension from local image upload names for consistency

Changes

New files

• src/features/editor/lib/imageUrlDetection.ts — sync image URL detection utilities (extension, domain, LRU cache)
• src/features/editor/api/imageUrlDetection.ts — frontend wrapper for Rust HEAD command
• src/features/editor/lib/__tests__/imageUrlDetection.test.ts — 30 unit tests
• vitest.config.ts — test runner configuration

Modified files

• src-tauri/src/link_preview.rs — add check_url_content_type command (HEAD with Range fallback)
• src-tauri/src/lib.rs — register new command in invoke_handler
• src-tauri/tauri.conf.json — add https: to CSP img-src for remote image display
• src/features/editor/hooks/useLinkPreview.ts — multi-stage paste handler with async title fallback
• src/features/editor/ui/Editor.tsx — move RenameDialog outside BlockNoteView
• src/features/editor/ui/RenameDialog.tsx — accept editor as prop, add PathRow component
• src/features/editor/ui/RenameButton.tsx — pass url prop to dialog state
• src/features/editor/api/imageUpload.ts — strip extension from uploaded image names

Test plan

• Paste HTTPS image URL (e.g. .jpg, .png) → image block rendered immediately
• Paste URL from known image hosting domain (imgur, etc.) → image block rendered
• Paste non-image URL → link inserted, title fetched asynchronously
• Image block name shows page title when available, filename fallback otherwise
• RenameDialog: Cancel/Save does not move cursor to end of note
• RenameDialog: name input is focusable and editable
• RenameDialog: path row truncates long paths, copy button works
• Local image paste → name shows filename without extension
• Existing functionality (local upload, link paste) unchanged

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