test: add adversarial unit tests for hooks system

[mattapperson]

Summary

• Adds 81 adversarial/edge-case unit tests across 5 test files targeting the hooks system from PR feat: add HooksManager lifecycle hook system to callModel #7
• Tests cover: handler chain execution, manager lifecycle, tool matchers, resolver normalization, and isAsyncOutput type guard

Findings surfaced

These tests document (not fix) real edge cases in the current implementation:

1. matchesTool — no boolean coercion: Function matchers returning truthy non-booleans (e.g. 1, null) pass the raw value through instead of true/false. Works with truthiness checks but fails strict === true comparisons.

2. matchesTool — global RegExp stateful .test(): Using a /g RegExp as a matcher causes alternating match/no-match results due to lastIndex state. The test documents this footgun.

3. executeHandlerChain — filter throws bypass error handling: Throwing filters propagate unhandled (they execute outside the try block), unlike throwing handlers which are caught in non-strict mode.

4. Re-entrant emit: A handler that registers a new handler mid-emit causes the new handler to execute in the same chain (since the for-loop reads entries.length dynamically).

5. block: "" (empty string) triggers short-circuit: isBlockTriggered checks typeof value === 'string', so empty strings count as blocks — potentially surprising.

Test files

File	Tests	Covers
hooks-emit-adversarial.test.ts	21	Empty inputs, primitive results, block edge cases, mutation piping, filter throws, async+block overlap, matcher interactions, stress test
hooks-manager-adversarial.test.ts	17	Double unsubscribe, re-entrant emit, custom hook validation, drain safety, removeAll during emit, sessionId changes
hooks-matchers-adversarial.test.ts	12	Empty strings, global RegExp, non-boolean returns, throwing matchers, regex-special chars in string matchers
hooks-resolve-adversarial.test.ts	13	Falsy inputs, empty config, malformed values, prototype pollution, arbitrary hook names
hooks-types-adversarial.test.ts	18	Non-boolean async values, non-object inputs, Proxy objects, arrays with async property, Object.create(null)

Test plan

• All 81 new adversarial tests pass
• All existing 186 unit tests still pass
• Build (pnpm build) passes