feat(electrobun): file management — CodeMirror editor, PDF viewer, CSV table, real file I/O

- CodeEditor: CodeMirror 6 with Catppuccin theme, 15+ languages, Ctrl+S save,
  dirty tracking, save-on-blur
- PdfViewer: pdfjs-dist canvas rendering, zoom 0.5-3x, HiDPI, lazy page load
- CsvTable: RFC 4180 parser, delimiter auto-detect, sortable columns, sticky header
- FileBrowser: real filesystem via files.list/read/write RPC, lazy dir loading,
  file type routing (code→editor, pdf→viewer, csv→table, images→display)
- 10MB size gate, binary detection, base64 encoding for non-text files

ui-electrobun/package.json

@@ -11,11 +11,26 @@
 		"build:canary": "vite build && electrobun build --env=canary"
 	},
 	"dependencies": {
+		"@codemirror/autocomplete": "^6.20.1",
+		"@codemirror/commands": "^6.10.3",
+		"@codemirror/lang-css": "^6.3.1",
+		"@codemirror/lang-html": "^6.4.11",
+		"@codemirror/lang-javascript": "^6.2.5",
+		"@codemirror/lang-json": "^6.0.2",
+		"@codemirror/lang-markdown": "^6.5.0",
+		"@codemirror/lang-python": "^6.2.1",
+		"@codemirror/lang-rust": "^6.0.2",
+		"@codemirror/language": "^6.12.2",
+		"@codemirror/search": "^6.6.0",
+		"@codemirror/state": "^6.6.0",
+		"@codemirror/theme-one-dark": "^6.1.3",
+		"@codemirror/view": "^6.40.0",
 		"@xterm/addon-canvas": "^0.7.0",
 		"@xterm/addon-fit": "^0.11.0",
 		"@xterm/addon-image": "^0.9.0",
 		"@xterm/xterm": "^6.0.0",
-		"electrobun": "latest"
+		"electrobun": "latest",
+		"pdfjs-dist": "^5.5.207"
 	},
 	"devDependencies": {
 		"@sveltejs/vite-plugin-svelte": "^5.0.1",