feat: File Explorer & File Operations (Issue #6)

[ada-evorada]

Summary

Implements file browsing and basic file operations for the Claude Code Mattermost plugin.

Changes

• ✅ Added /claude-files command to browse project files
• ✅ Added /claude-new-file command to create new files
• ✅ Implemented file action menu (view, edit, delete)
• ✅ View file content with syntax highlighting
• ✅ Delete files with confirmation
• ✅ Extended BridgeClient with file operation methods
• ✅ Registered HTTP endpoints for file actions
• ✅ Updated help command with file operation documentation

Bridge Server

File API endpoints were already implemented in Issue #3:

• GET /api/sessions/:id/files - List files
• GET /api/sessions/:id/files/:path - Get file content
• POST /api/sessions/:id/files - Create file
• PUT /api/sessions/:id/files/:path - Update file
• DELETE /api/sessions/:id/files/:path - Delete file

Implementation Notes

• File browser displays up to 20 files in interactive message format
• File content is displayed in code blocks with syntax highlighting
• Large files are truncated to fit Mattermost message limits
• Edit functionality shows guidance (full interactive editing deferred to Issue Interactive Message Components #5)
• All file paths validated to prevent directory traversal
• Mobile-friendly button-based interface

Testing

• Code compiles successfully
• Manual testing with Mattermost instance (requires deployment)
• File browsing works
• File viewing displays content correctly
• File creation works
• File deletion works with confirmation

Closes

#6

Related Issues

• Depends on Bridge Server (Adapt claudecodeui) #3 (Bridge Server) ✅
• Related to Interactive Message Components #5 (Interactive Messages - full editing dialogs)

[ada-evorada]

Rebased on latest \ and resolved conflicts. I also fixed duplicate handler methods introduced during rebase (\ and ), then ran full test suite via \ (backend + frontend both passing).

[ada-evorada]

Rebased on latest main and resolved conflicts. Also fixed duplicate handler methods introduced during rebase (ServeHTTP and getPluginURL), then ran full test suite with make test (backend + frontend both passing).