Switch from whitelist to blacklist pattern for determining editable files.
Files are now editable unless they are known binary types (audio, archives,
executables, Office documents, fonts, etc.), enabling support for any
runtime-generated text files without needing to add extensions one by one.
Remove the Office file placeholder that only showed "Preview will be
supported in a future update" without any download option. Office files
(pdf, doc, docx, xls, xlsx, ppt, pptx) now fall through to the generic
"unsupported file" handler which provides a download button.
Removed:
- OfficeFilePlaceholder component
- isOfficeFile function and OFFICE_EXTENSIONS constant
- isOffice flag from useFileTypeInfo hook
- i18n keys for officePlaceholder
This simplifies the file type handling to just three categories:
- Editable: markdown, code, text files → editor
- Previewable: image, video files → media preview
- Everything else: download button
- Extract useFileOperations hook to hooks/use-file-operations.ts
- Move tree utilities to utils/tree-utils.ts
- Move file utilities to utils/file-utils.ts (renamed from utils.ts)
- Remove unnecessary JSDoc comments throughout components
- Simplify type.ts to only contain local type definitions
- Clean up store/index.ts by removing verbose comments
