feat: list available skills when running /skill with no args

- Add list_skills Tauri command to scan ~/.claude/skills/
- Only lists directories containing a SKILL.md file
- Show helpful message when no skills are found
- Display bullet-point list of available skills with usage hint

src-tauri/src/commands.rs

@@ -180,3 +180,45 @@ pub async fn answer_question(
     let mut manager = bridge_manager.lock();
     manager.send_tool_result(&conversation_id, &tool_use_id, answers)
 }
+
+#[tauri::command]
+pub async fn list_skills() -> Result<Vec<String>, String> {
+    use std::path::Path;
+    use std::fs;
+
+    // Get the home directory
+    let home = std::env::var_os("HOME")
+        .ok_or_else(|| "Could not determine home directory".to_string())?;
+
+    let skills_dir = Path::new(&home).join(".claude").join("skills");
+
+    // If the skills directory doesn't exist, return empty list
+    if !skills_dir.exists() {
+        return Ok(Vec::new());
+    }
+
+    // Read the directory and collect skill names
+    let mut skills = Vec::new();
+    let entries = fs::read_dir(&skills_dir)
+        .map_err(|e| format!("Failed to read skills directory: {}", e))?;
+
+    for entry in entries {
+        let entry = entry.map_err(|e| format!("Failed to read directory entry: {}", e))?;
+        let path = entry.path();
+
+        // Only include directories that contain a SKILL.md file
+        if path.is_dir() {
+            let skill_file = path.join("SKILL.md");
+            if skill_file.exists() {
+                if let Some(name) = path.file_name() {
+                    skills.push(name.to_string_lossy().to_string());
+                }
+            }
+        }
+    }
+
+    // Sort alphabetically
+    skills.sort();
+
+    Ok(skills)
+}