fix(remote): harden account device control

[bobleer]

Summary

• fix account device deletion failures and make deleting the current device revoke its session, remove it from the account, and log out locally
• harden relay authentication, delegated-token scopes, tenant isolation, pairing replay protection, WebSocket origin/rate limits, storage quotas, asset paths, and database migration behavior
• improve desktop, mobile web, and CLI remote-control states, recovery messages, confirmation flows, connection health, localization, CSP, and embedded mobile assets
• eliminate the existing desktop Rust warnings and Web ESLint warnings; split the mobile chat route and register Prism languages explicitly to remove the mobile production bundle warning

Validation

• cargo check --workspace --message-format=short
• cargo test -p bitfun-relay-service --message-format=short (40 passed)
• cargo test -p bitfun-core remote_connect --message-format=short (49 unit + 2 host-boundary passed)
• cargo test -p bitfun-cli --message-format=short (303 unit tests plus integration suites passed)
• cargo test -p bitfun-desktop --message-format=short (175 passed, 2 permission-dependent ignored)
• cargo test -p bitfun-relay-server --test library_compat --message-format=short
• pnpm run type-check:web
• pnpm run lint:web
• focused Web Vitest suite (8 files, 107 passed)
• pnpm --dir src/mobile-web run type-check
• pnpm run build:mobile-web
• pnpm run check:repo-hygiene
• git diff --check

Notes

The branch is rebased onto the current upstream main. The two ignored desktop tests require macOS Accessibility permission and are unchanged permission-gated checks.