* refactor: move WhatsApp channel from src/web/ to extensions/whatsapp/
Move all WhatsApp implementation code (77 source/test files + 9 channel
plugin files) from src/web/ and src/channels/plugins/*/whatsapp* to
extensions/whatsapp/src/.
- Leave thin re-export shims at all original locations so cross-cutting
imports continue to resolve
- Update plugin-sdk/whatsapp.ts to only re-export generic framework
utilities; channel-specific functions imported locally by the extension
- Update vi.mock paths in 15 cross-cutting test files
- Rename outbound.ts -> send.ts to match extension naming conventions
and avoid false positive in cfg-threading guard test
- Widen tsconfig.plugin-sdk.dts.json rootDir to support shim->extension
cross-directory references
Part of the core-channels-to-extensions migration (PR 6/10).
* style: format WhatsApp extension files
* fix: correct stale import paths in WhatsApp extension tests
Fix vi.importActual, test mock, and hardcoded source paths that weren't
updated during the file move:
- media.test.ts: vi.importActual path
- onboarding.test.ts: vi.importActual path
- test-helpers.ts: test/mocks/baileys.js path
- monitor-inbox.test-harness.ts: incomplete media/store mock
- login.test.ts: hardcoded source file path
- message-action-runner.media.test.ts: vi.mock/importActual path
