fix(db): attribute huddle_started_links pool acquisition (#7112 regression)

[rebekz]

Problem

huddle_started_links (crates/buzz-db/src/store/event.rs) calls .fetch_all(pool) directly, bypassing the typed pool-acquisition attribution that the rest of the event store uses. This trips the repo's own guard:

observability_source::p0_pool_acquisitions_use_typed_operation_pairs_without_other

Introduced in c6ca9d9 ("Show status and huddle indicators beside names", #7112).

Why CI did not catch it

The guard commit 91ab9d31b predates #7112 by one day, so that PR's CI either did not run the guard or did not enforce its failure. Worth a look independently of this patch — the guard is currently not protecting main.

Fix

Acquire the connection through the existing WriterOperation::SubscriptionHistory label, matching the convention already used by the neighbouring query_events / count / get_last_message_at subscription-history reads in the same file, where replica routing does not select a reader.

SQL, binds, returned rows, ordering, and propagated errors are unchanged — this is attribution only.

Verification

• Guard observed failing on the unmodified line, then passing after the change (both directions observed, so the check discriminates).
• cargo clippy --workspace --all-targets -- -D warnings clean.

🤖 Generated with Claude Code

[github-actions]

🔐 Codex Security Review

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