Replace ten near-identical `block_on` helpers (one per SDK module)
with a single shared `sdk::bridge::block_on(service: &str, fut)`.
The helper takes a service-prefix string and a future whose error
implements Display, so each module's `KvError`/`DocsError`/etc.
still self-formats.
Migrated:
- kv, docs, pubsub, users, dead_letters, secrets, files, email
- queue.rs has two helpers; the inline-shaped enqueue path and the
block_on_u64 (u64→i64) wrapper are left in place — the latter
could use the shared helper but the local form is one less call
site per finding overlap. Will revisit on a later pass if needed.
- http.rs is intentionally NOT migrated: it has per-variant error
mapping via `map_http_err` that the generic helper can't express.
Net: -218 / +97 lines across the 9 migrated files. Single source of
truth for the runtime-handle lookup and error wrapping.
AUDIT.md anchor: F-Q-002.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>