fix(enrichment): restart cancelled repairs and execute durable retries

[stef-k]

Cancelled enrichment previously offered no retry/repair path despite eligible work. Enable the distinct explicit Retry and Repair commands from Cancelled, align prepared-repair progress with worker eligibility, and execute transient repairs through durable due-time Quartz continuations. Preserve cancellation fencing and replacement-operation ownership, and show outcome-supported locality-free feedback without automatic repeated contacts.

Includes import documentation and Unreleased notes. Closes #566. No database migrations or configuration changes. Preserves #565 behavior.

Validation:

• Independent review of d8d4073: READY FOR PR, no current-branch product blocker. The subsequent 871640e commit only corrects one contradictory documentation sentence; diff and guard checks passed.
• Reviewer freshly built and passed 289 focused tests, zero failures/skips, including relational commands, due-time continuation, cancellation/replacement ownership, rendering, manual-edit preservation, and authenticated SSE.
• Retained behavioral red logs inspected; overlapping test runs are not additive.
• Code Guard covered all 23 files with no FAIL/INCOMPLETE. Accepted size REVIEWs: unchanged 500-LOC atomicity allowance; linear continuation/orphan and existing Quartz lifecycle tests; historical changelog.
• No browser observation or screenshot was captured; presentation is covered by rendering tests.

Explicit validation debt: #568 tracks the pre-existing shared-domain isolation and stopped-scheduler cleanup defects in RetryProjectionFailureReconcilesOnceAndDoesNotReplayAfterRestart. This test was explicitly excluded from the 289-test selection after encountering 207 unrelated workflows. Isolated Quartz tables do not isolate domain reconciliation; filtering only assertions is insufficient. The persistent restart/no-replay proof and full-suite success remain unestablished. No unrelated database rows were removed.

The accelerated continuation proof exercises the actual Quartz/job/worker after moving stored deadlines; it does not prove five minutes of unattended waiting or persistent-store restart. Original production inactivity remains unconfirmed. Local reproductions establish progress omission and continuation defects, not reconstruction of the production session.

Merge gate: successful GitHub Actions test on the exact current PR head. Retain #568 debt in merge notes.