test(app): mock navigateToSession in the session presentation test

[rophy]

Summary. sources/components/sessionPresentation.test.ts no longer loads: since 051c228, session/[id]/info.tsx imports navigateToSession from @/hooks/useNavigateToSession, which imports @/track → expo-constants → expo-modules-core, and that fails under vitest with ReferenceError: __DEV__ is not defined. None of the file's 19 tests run. CI does not run the app's unit tests, so it went unnoticed. This PR mocks @/hooks/useNavigateToSession in the test, like its other hook mocks.

Proof (pnpm --filter happy-app exec vitest run sources/components/sessionPresentation.test.ts)

main (dafe9a51):  ReferenceError: __DEV__ is not defined   Tests: no tests
051c2280^:        Tests: 19 passed (19)
this PR:          Tests: 19 passed (19)

Full app suite on this branch: 171 files, 1946 passed, 1 skipped.

[chphch]

Reproduced and verified on current main (18ae87e):

• without this PR, sessionPresentation.test.ts fails to load (ReferenceError: __DEV__ is not defined) and none of its 19 tests run
• with this one line on top of 18ae87e, the file passes 19/19 and the full app suite passes (171 files, 1946 tests, 1 skipped)