feat: add Files tab for browsing workspace files (#154)

* feat: add Files tab for browsing workspace files

- Add Files tab between Diff and Terminal in header
- Implement hierarchical file tree with expand/collapse
- Add fuzzy search with debouncing and relevance ranking
- Support gitignore filtering via `git check-ignore` (web + desktop)
- Add syntax highlighting for 150+ file types
- Add image preview (SVG, PNG, JPG, etc.)
- Add line numbers, wrap toggle, and copy button
- Desktop: split-pane layout matching DiffView
- Mobile: drill-in navigation with full-width sidebar
- Update help dialog with Cmd+3 shortcut
- Increase header breakpoint to 940px for new tab

* feat: enhance context and session stores to track agent/model/variant choices for historical sessions

* feat: implement line selection and commenting functionality in FilesView

packages/desktop/src-tauri/src/main.rs

@@ -28,7 +28,7 @@ use axum::{
     routing::{any, get, post},
     Json, Router,
 };
-use commands::files::{create_directory, exec_commands, list_directory, read_file, search_files, write_file};
+use commands::files::{create_directory, exec_commands, list_directory, read_file, read_file_binary, search_files, write_file};
 use commands::git::{
     add_git_worktree, check_is_git_repository, checkout_branch, create_branch, create_git_commit, rename_branch,
     create_git_identity, delete_git_branch, delete_git_identity, delete_remote_branch,
@@ -836,6 +836,7 @@ fn main() {
             search_files,
             create_directory,
             read_file,
+            read_file_binary,
             write_file,
             exec_commands,
             request_directory_access,