feat(permissions): implement permission system with plan mode enforcement (M1 complete)

This commit implements the complete M1 milestone (Config & Permissions) including:

- New permissions crate with Tool, Action, Mode, and PermissionManager
- Three permission modes: Plan (read-only default), AcceptEdits, Code
- Pattern matching for permission rules (exact match and prefix with *)
- Integration with config-agent for mode-based permission management
- CLI integration with --mode flag to override configured mode
- Permission checks for Read, Glob, and Grep operations
- Comprehensive test suite (10 tests in permissions, 4 in config, 4 in CLI)

Also fixes:
- Fixed failing test in tools-fs (glob pattern issue)
- Improved glob_list() root extraction to handle patterns like "/*.txt"

All 21 workspace tests passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

crates/platform/config/src/lib.rs

@@ -5,6 +5,7 @@ use figment::{
 };
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
+use permissions::{Mode, PermissionManager};
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Settings {
@@ -39,6 +40,19 @@ impl Default for Settings {
     }
 }
 
+impl Settings {
+    /// Create a PermissionManager based on the configured mode
+    pub fn create_permission_manager(&self) -> PermissionManager {
+        let mode = Mode::from_str(&self.mode).unwrap_or(Mode::Plan);
+        PermissionManager::new(mode)
+    }
+
+    /// Get the Mode enum from the mode string
+    pub fn get_mode(&self) -> Mode {
+        Mode::from_str(&self.mode).unwrap_or(Mode::Plan)
+    }
+}
+
 pub fn load_settings(project_root: Option<&str>) -> Result<Settings, figment::Error> {
     let mut fig = Figment::from(Serialized::defaults(Settings::default()));