Expose aggregate lifecycle progress diagnostics

[callumalpass]

Summary

• add an internally authenticated, aggregate-only Connect lifecycle diagnostics endpoint for cleanup and application-reconciliation work
• extend hosted-provider diagnostics schema v2 with independently unavailable outbox, mutation-journal, and stuck-deletion aggregates
• use bounded read-only database transactions, database time, fixed thresholds, and privacy-safe section responses
• bootstrap observability only; no promotion enforcement, global equality scan, customer identifiers, or deployment changes

Verification

• workspace typecheck and pnpm test:fast passed on the rebased publication branch
• strict all-target/all-feature Clippy and formatting passed
• Connect production PostgreSQL aggregate matrix passed in a UUID-scoped loopback test schema
• provider production PostgreSQL aggregate matrix passed with exact destructive-test approval and unconditional schema cleanup
• independent adversarial audit: ACCEPT

[callumalpass]

Deliberately dequeued after full merge qualification exposed a pre-existing authority-import completion race in disposable provider E2E. Runs 33123674683 and 33126616897 returned, respectively, false authority_import_target_unavailable and projection_lease_unavailable conflicts while the recovery finalizer raced the same idempotent completion. The authority remained fenced, but a green scheduling rerun would not satisfy the resumable-completion contract. A focused deterministic correction is in progress under the local campaign record authority-import-finalizer-races-idempotent-completion; this PR will be requeued after that correction merges.