fix(ci): simplify test runner to plain bun test by fixing mock.module() leakage

- Add afterAll(() => { mock.restore() }) to 52 test files missing cleanup
- Rewrite create-tool-guard-hooks.test.ts to use spyOn instead of barrel mock
- Fix skill-mcp-manager OAuth tests with missing mockTokens/mockLogin definitions
- Fix start-work hook: show worktree active block on resume with existing worktree_path
- Extract createWorktreeActiveBlock to worktree-block.ts to avoid circular import
- Replace 80-line isolated test runner CI config with single `bun test` command

src/plugin/event.model-fallback.test.ts

@@ -1,11 +1,13 @@
 declare const require: (name: string) => any
-const { afterEach, describe, expect, mock, test } = require("bun:test")
+const { afterEach, afterAll, describe, expect, mock, test } = require("bun:test")
 
 mock.module("../shared/connected-providers-cache", () => ({
   readConnectedProvidersCache: () => null,
   readProviderModelsCache: () => null,
 }))
 
+afterAll(() => { mock.restore() })
+
 import { createEventHandler } from "./event"
 import { createChatMessageHandler } from "./chat-message"
 import { _resetForTesting, setMainSession } from "../features/claude-code-session-state"