feat(ui): add file icon resolver with Nerd/ASCII sets, env override, and breadcrumb display

- Introduce `IconMode` in core config (default Auto) and bump schema version to 1.4.0.
- Add `FileIconSet`, `IconDetection`, and `FileIconResolver` to resolve per‑file icons with configurable fallbacks and environment variable `OWLEN_TUI_ICONS`.
- Export resolver types from `owlen-tui::state::file_icons`.
- Extend `ChatApp` with `file_icons` field, initialize it from config, and expose via `file_icons()` accessor.
- Append system status line showing selected icon set and detection source.
- Implement breadcrumb construction (`repo > path > file`) and display in code pane headers.
- Render icons in file tree, handle unsaved file markers, hidden files, and Git decorations with proper styling.
- Add helper `collect_unsaved_relative_paths` and tree line computation for visual guides.
- Provide `Workspace::panes()` iterator for unsaved tracking.
- Update UI imports and tests to cover new breadcrumb feature.

crates/owlen-tui/src/chat_app.rs

@@ -28,10 +28,10 @@ use crate::config;
 use crate::events::Event;
 use crate::model_info_panel::ModelInfoPanel;
 use crate::state::{
-    CodeWorkspace, CommandPalette, FileFilterMode, FileNode, FileTreeState, ModelPaletteEntry,
-    PaletteSuggestion, PaneDirection, PaneRestoreRequest, RepoSearchMessage, RepoSearchState,
-    SplitAxis, SymbolSearchMessage, SymbolSearchState, WorkspaceSnapshot, spawn_repo_search_task,
-    spawn_symbol_search_task,
+    CodeWorkspace, CommandPalette, FileFilterMode, FileIconResolver, FileNode, FileTreeState,
+    ModelPaletteEntry, PaletteSuggestion, PaneDirection, PaneRestoreRequest, RepoSearchMessage,
+    RepoSearchState, SplitAxis, SymbolSearchMessage, SymbolSearchState, WorkspaceSnapshot,
+    spawn_repo_search_task, spawn_symbol_search_task,
 };
 use crate::ui::format_tool_output;
 // Agent executor moved to separate binary `owlen-agent`. The TUI no longer directly
@@ -224,6 +224,7 @@ pub struct ChatApp {
     resize_snap_index: usize,           // Cycles through 25/50/75 snaps
     last_snap_direction: Option<PaneDirection>,
     file_tree: FileTreeState,                    // Workspace file tree state
+    file_icons: FileIconResolver,                // Icon resolver with Nerd/ASCII fallback
     file_panel_collapsed: bool,                  // Whether the file panel is collapsed
     file_panel_width: u16,                       // Cached file panel width
     saved_sessions: Vec<SessionMeta>,            // Cached list of saved sessions
@@ -384,6 +385,7 @@ impl ChatApp {
         let show_cursor_outside_insert = config_guard.ui.show_cursor_outside_insert;
         let syntax_highlighting = config_guard.ui.syntax_highlighting;
         let show_timestamps = config_guard.ui.show_timestamps;
+        let icon_mode = config_guard.ui.icon_mode;
         drop(config_guard);
         let theme = owlen_core::theme::get_theme(&theme_name).unwrap_or_else(|| {
             eprintln!("Warning: Theme '{}' not found, using default", theme_name);
@@ -392,6 +394,7 @@ impl ChatApp {
 
         let workspace_root = std::env::current_dir().unwrap_or_else(|_| PathBuf::from("."));
         let file_tree = FileTreeState::new(workspace_root);
+        let file_icons = FileIconResolver::from_mode(icon_mode);
 
         let mut app = Self {
             controller,
@@ -454,6 +457,7 @@ impl ChatApp {
             resize_snap_index: 0,
             last_snap_direction: None,
             file_tree,
+            file_icons,
             file_panel_collapsed: true,
             file_panel_width: 32,
             saved_sessions: Vec::new(),
@@ -479,6 +483,12 @@ impl ChatApp {
             show_message_timestamps: show_timestamps,
         };
 
+        app.append_system_status(&format!(
+            "Icons: {} ({})",
+            app.file_icons.status_label(),
+            app.file_icons.detection_label()
+        ));
+
         app.update_command_palette_catalog();
 
         if let Err(err) = app.restore_workspace_layout().await {
@@ -973,6 +983,10 @@ impl ChatApp {
         &mut self.file_tree
     }
 
+    pub fn file_icons(&self) -> &FileIconResolver {
+        &self.file_icons
+    }
+
     pub fn workspace(&self) -> &CodeWorkspace {
         &self.code_workspace
     }