refactor(interests): drop pipelineStage='completed' sentinel convention

`outcome` is the canonical terminal-state signal. Pre-2026-05-14
`setInterestOutcome` also forced `pipelineStage='completed'` (a value
outside the 7-stage canon) which:

- broke `safeStage()` (silently coerced to 'enquiry' downstream)
- prevented analytics from answering "what stage was the deal at when
  it closed?" because every closed deal looked identical
- forced belt-and-suspenders filters everywhere ('outcome=won' AND
  'pipeline_stage=completed') that became redundant after migration 0062

Changes:

- `setInterestOutcome` no longer touches pipelineStage. Deal stays at
  whatever stage it was on when the outcome was recorded; outcome is
  the terminal signal. Audit log + websocket emit now carry
  `stageAtOutcome` instead of the stale `oldStage`.

- `clearInterestOutcome` smarter reopen-stage logic: if current stage
  is the legacy 'completed' sentinel (pre-existing rows from before
  this commit), default to 'qualified'. Otherwise preserve the stage
  the deal was at, so reopening drops the rep back where they were.
  Explicit data.reopenStage still wins.

- `/api/v1/admin/dashboard-stats` route reworked: per-stage breakdown
  now filters `outcome IS NULL` (only active rows count per stage);
  `closedTotal` derives from a new `outcome IS NOT NULL` count query;
  `completed30d` switches from `pipelineStage='completed' AND updatedAt`
  to `outcome IS NOT NULL AND outcomeAt` (avoids long-closed deals
  leaking into the window on unrelated edits).

- `berth-interests-tab.tsx` "active" filter switches from
  `pipelineStage !== 'completed'` to `!outcome && !archivedAt` — the
  legacy check stopped matching post-refactor.

- Socket event type `interest:outcomeSet` renames `oldStage` →
  `stageAtOutcome` with a doc-comment explaining the semantics shift.

PIPELINE_STAGES canon is now the only valid pipeline_stage value range
for newly-set outcomes. Legacy rows still carry 'completed' until they
naturally churn through reopen + re-close, at which point they enter
the new convention.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/berths/berth-interests-tab.tsx

@@ -75,7 +75,11 @@ export function BerthInterestsTab({ berthId }: BerthInterestsTabProps) {
   const rows = useMemo<InterestRow[]>(() => {
     const all = data?.data ?? [];
     const filtered = all.filter((i) => {
-      if (stage === 'active') return i.pipelineStage !== 'completed' && !i.archivedAt;
+      // 2026-05-14 sentinel-stage cleanup: an interest is "active" when
+      // it has no terminal outcome and isn't archived. The legacy
+      // `pipelineStage !== 'completed'` check stopped working after the
+      // 7-stage refactor stopped writing 'completed' for terminal rows.
+      if (stage === 'active') return !i.outcome && !i.archivedAt;
       if (stage === 'lost') return Boolean(i.archivedAt);
       return true;
     });