feat(plugins): add advanced plugin system with full TUI customization (#551)

* feat(plugins): add TUI event hooks for plugin system

* feat(plugins): expand UI hooks with advanced TUI customization types

- Add UiRegion enum for content injection zones (header, footer, sidebars, overlays)
- Add comprehensive style types: Color, TextStyle, WidgetStyle, BorderStyle
- Add WidgetSize/WidgetConstraints for layout control
- Expand UiWidget with Text, List, Table, Gauge, Sparkline, layouts, Block
- Add keyboard binding types: KeyBinding, KeyModifier, KeyBindingResult
- Add ThemeColors and ThemeOverride for dynamic theming
- Add hooks: WidgetRegisterHook, KeyBindingHook, ThemeOverrideHook
- Add LayoutCustomizeHook with LayoutPanel and LayoutDirection
- Add ModalInjectHook with ModalDefinition and ModalLayer
- Add ToastShowHook with ToastDefinition and ToastLevel
- All public types documented, 9 unit tests passing

* feat(plugins): add new UI and TUI event hook types to HookType enum

* feat(plugins/sdk): add hot-reload support and comprehensive templates

- Add TypeScript template for JS/TS plugin development
- Add tsconfig.json template for TypeScript plugins
- Add hot-reload configuration template with watch patterns and debounce
- Add testing utilities template with MockContext and MockToolInput
- Add advanced Rust template with TUI hooks, widgets, and keybindings
- Add HotReloadConfig struct with builder pattern
- Add scaffold_advanced() method for advanced plugin scaffolding
- Add tests for all new generator functions

* feat(plugins): expand hook registry with full TUI hook support

Add comprehensive hook registration support for all TUI-related hooks:
- UI hooks: UiRender, WidgetRegister, KeyBinding, ThemeOverride,
  LayoutCustomize, ModalInject, ToastShow
- TUI event hooks: TuiEventSubscribe, TuiEventDispatch,
  CustomEventEmit, EventIntercept, AnimationFrame
- Additional hooks: CommandExecuteBefore/After, InputIntercept,
  SessionStart/End, FocusChange

Each hook type includes:
- Registered hook wrapper struct with plugin_id, hook, and priority
- Registration method with priority-based sorting
- Unregistration support via unregister_plugin()
- Hook count tracking via hook_count() and total_hook_count()
- Plugin tracking via registered_plugins()

* feat(plugins): update lib.rs exports with TUI events and SDK types

* feat(plugins): add command completion hooks for plugin autocompletion

* feat(plugins): export completion hooks in lib.rs

* security(plugins): fix critical security vulnerabilities in plugin system

WASM Runtime DoS Protection:
- Add fuel-based CPU limiting (10M operations max)
- Add epoch interruption support for timeout handling
- Implement ResourceLimiter with 16MB memory cap
- Add table/instance/memory limits
- Remove panic-prone Default impl for WasmRuntime

Path Traversal Prevention:
- Canonicalize all paths before access checks
- Resolve symlinks to prevent traversal via symlinks
- Validate paths stay within allowed boundaries
- Handle non-existent paths safely for write operations

Fail-Closed Security Model:
- Empty command allowlist now denies all commands
- Empty domain allowlist now denies all network access
- None allowed_domains denies network access
- Explicit opt-in required via '*' wildcard

SSRF Protection:
- Block localhost/loopback addresses (127.0.0.1, ::1, etc.)
- Block private IP ranges (10.x, 172.16-31.x, 192.168.x)
- Block link-local addresses (169.254.x.x)
- Block .local/.internal domain suffixes
- Block dangerous ports (SSH, databases, etc.)
- Allow only http/https protocols

Permission Hook Security:
- Document security implications of Allow decision
- Add requires_elevated_trust() method
- Add validate_for_third_party() method

Hook Priority Security:
- Reserve priorities 0-49 for system use
- Add SYSTEM_CRITICAL, SYSTEM, SYSTEM_HIGH constants
- Add PLUGIN_MIN (50), PLUGIN_HIGH (75) for third-party
- Add validate_for_plugin() method
- Deprecate HIGHEST/HIGH in favor of explicit names

SDK Safety Documentation:
- Add SAFETY comments to all unsafe FFI calls
- Document host contract assumptions

Author: echobt

Cargo.lock

@@ -19,6 +19,7 @@ toml = { workspace = true }
 
 # Error handling
 thiserror = { workspace = true }
+anyhow = { workspace = true }
 
 # Logging
 tracing = { workspace = true }