[Epic] Expo migration follow-ups & dev tooling

[mattrace-gloo]

Summary

Epic tracking Expo-migration follow-ups and dev tooling on the Expo SDK 56 CNG (Android-only) baseline: env validation, a real DB migration framework, jest-expo test mocks, onboarding docs, the API client standard, and lint guardrails. Several items are already partly done on main and are reframed to "harden/extend":

• F1 (Env audit + typed runtime validation #109) env standardization — done (apiBaseUrl.ts, env.d.ts; no @env).
• F3 (Expo test infra (jest-expo mocks, gate fluent-api.test.ts) #111) jest-expo is already the preset → add native-module mocks + gate the live fluent-api.test.ts.
• F4 (EAS/dev-client onboarding + prebuild docs #112) EAS/preview docs — done (onboarding + preview-build loop documented).
• F6 (Lint guardrails for handoff anti-patterns #114) no-console/logger rule already exists → add guardrails for the Newbase Branch #82 anti-patterns.

Genuinely net-new: F2 (#110) migration framework, F5 (#113) API client standard.

Sub-issues

• Env audit + typed runtime validation #109
• DB migration framework #110
• Expo test infra (jest-expo mocks, gate fluent-api.test.ts) #111
• EAS/dev-client onboarding + prebuild docs #112
• API client architecture standard #113
• Lint guardrails for handoff anti-patterns #114

Dependency ordering

• DB migration framework #110 (F2) is foundational and blocks C1 (Recordings linkage + restore chapter_assignment FK/index via migration #99) and D1 (Harden multi-user schema: FKs/indexes via migration #103) schema migrations — land early.
• Expo test infra (jest-expo mocks, gate fluent-api.test.ts) #111 (F3) mocks support A2/B/C unit tests — land alongside DB migration framework #110.
• Env audit + typed runtime validation #109 (F1) — done.
• API client architecture standard #113 (F5) builds on A1 (Harden API token injection (remove mutable singleton + fake async) #88).
• EAS/dev-client onboarding + prebuild docs #112 (F4) and Lint guardrails for handoff anti-patterns #114 (F6) are smaller; can land independently.

Links

• Anti-pattern reference only (not merging): PR #82