test(tools): add effectiveContextSize to the llm mock (fixes CI test gate)

tools.ts:323 calls llm.effectiveContextSize() to budget tool schemas to the
context window, but tools-stream.test.ts mocked ../llm with only { init,
streamChat } - so all 13 tests threw "effectiveContextSize is not a function".
Add it to the mock (returns a roomy 8192 so budgeting takes its normal no-prune
path). This is CI's hard gate (npm test); lint stays advisory in ci.yml.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01U2S44L2JTARo75RQNRXH54

Author: Anurag-Wednesday

src/main/__tests__/tools-stream.test.ts

@@ -9,7 +9,9 @@ const { streamChatMock, initMock } = vi.hoisted(() => ({
   streamChatMock: vi.fn(),
   initMock: vi.fn().mockResolvedValue(undefined),
 }));
-vi.mock('../llm', () => ({ llm: { init: initMock, streamChat: streamChatMock } }));
+// effectiveContextSize() is called by toolChat to budget tool schemas to the window.
+// Return a roomy fixed size so budgeting takes its normal (no-prune) path under test.
+vi.mock('../llm', () => ({ llm: { init: initMock, streamChat: streamChatMock, effectiveContextSize: () => 8192 } }));
 const { getSettingMock, saveSettingMock } = vi.hoisted(() => ({ getSettingMock: vi.fn(() => [] as string[]), saveSettingMock: vi.fn() }));
 vi.mock('../database', () => ({ getSetting: getSettingMock, saveSetting: saveSettingMock }));