fix: address PR #4180 review - security, typing, and test coverage

- Apply mcp_env_allowlist to plugin hooks: intersect HTTP allowedEnvVars
  with MCP allowlist, set command allowedEnvVars to full MCP allowlist
- Scrub process.env in executeHookCommand when allowedEnvVars provided
- Add PluginHooksState class with per-directory Map storage
- Add PluginHooksConfig interface for typed boundary layer
- Pass directory context through hook-config-handler
- Add 16 tests across 4 files (40 assertions) covering allowlist
  filtering, env scrubbing, directory isolation, and edge cases
- Remove unnecessary 'as' type assertions, use discriminated union
  narrowing instead

src/plugin-handlers/plugin-components-loader.ts

@@ -1,5 +1,6 @@
 import type { OhMyOpenCodeConfig } from "../config";
 import { loadAllPluginComponents } from "../features/claude-code-plugin-loader";
+import type { PluginHooksConfig } from "../hooks/claude-code-hooks/types";
 import { addConfigLoadError, log } from "../shared";
 
 export type PluginComponents = {
@@ -7,7 +8,7 @@ export type PluginComponents = {
   skills: Record<string, unknown>;
   agents: Record<string, unknown>;
   mcpServers: Record<string, unknown>;
-  hooksConfigs: Array<{ hooks?: Record<string, unknown> }>;
+  hooksConfigs: PluginHooksConfig[];
   plugins: Array<{ name: string; version: string }>;
   errors: Array<{ pluginKey: string; installPath: string; error: string }>;
 };