Phase 1 — Platform SDK integration:
- Mobile: added @bytelyst/telemetry-client, feature-flag-client, kill-switch-client, blob-client deps
- Mobile: created src/lib/platform.ts — centralized platform init (telemetry, flags, kill-switch, blob)
- Mobile: wired initPlatform() into root layout startup
- Web: refactored blob-client.ts to use shared @bytelyst/blob-client (eliminates hand-rolled SAS fetch code)
- Web: added @bytelyst/blob-client dep
DRY: Both web and mobile now use the same @bytelyst/blob-client package for blob operations.
Verification: web typecheck + mobile typecheck pass.
