feat(hooks): add HTTP hook handler support

Add type: "http" hook support matching Claude Code's HTTP hook specification.
HTTP hooks send POST requests with JSON body, support env var interpolation
in headers via allowedEnvVars, and configurable timeout.

New files:
- execute-http-hook.ts: HTTP hook execution with env var interpolation
- dispatch-hook.ts: Unified dispatcher for command and HTTP hooks
- execute-http-hook.test.ts: 14 tests covering all HTTP hook scenarios

Modified files:
- types.ts: Added HookHttp interface, HookAction union type
- config.ts: Updated to accept HookAction in raw hook matchers
- pre-tool-use/post-tool-use/stop/user-prompt-submit/pre-compact:
  Updated all 5 executors to dispatch HTTP hooks via dispatchHook()
- plugin-loader/types.ts: Added "http" to HookEntry type union

src/hooks/claude-code-hooks/config.ts

@@ -1,12 +1,12 @@
 import { join } from "path"
 import { existsSync } from "fs"
 import { getClaudeConfigDir } from "../../shared"
-import type { ClaudeHooksConfig, HookMatcher, HookCommand } from "./types"
+import type { ClaudeHooksConfig, HookMatcher, HookAction } from "./types"
 
 interface RawHookMatcher {
   matcher?: string
   pattern?: string
-  hooks: HookCommand[]
+  hooks: HookAction[]
 }
 
 interface RawClaudeHooksConfig {