feat: add Telegram profile deletion

[dKosarevsky]

Summary

• add atomic, idempotent Telegram profile deletion while preserving the current opaque token as a guest session
• add accessible two-step deletion UI, recovery behavior, race proofs, E2E coverage, and production artifact leak checks
• document privacy boundaries, retained pseudonymous fields, and the production release gate

Test plan

• npm run check
• npm run typecheck
• npm test (766 tests)
• npm run content:validate
• API, Pages, and Android web builds
• artifact verification
• Playwright E2E (5/5)