fix(ux): T4 polish wave — empty-contact filter, redirect-on-create, friendly stage errors

F19: client form drops empty-value contacts on submit; auto-promotes first remaining row to primary if none flagged.
F20: new-interest dialog redirects to the detail page on create instead of bouncing back to the list.
F21: stage-transition validation errors render with STAGE_LABELS — "Yacht is required before leaving the Enquiry stage." (was "yachtId is required before leaving stage=enquiry").
F22: blocked-stage marker swapped from the ⚑ unicode glyph to a Lucide AlertTriangle with aria-label.
F25: documents-hub folder selection moves to ?folder=<id> querystring so deep-link / browser-back / refresh round-trip the current folder.
F26: reopen-outcome action now toasts "Outcome cleared — interest is open again."
F27: stage PATCH where target === current short-circuits to a no-op return; downstream callers don't see a phantom stage_change audit row.

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

src/lib/services/interests.service.ts

@@ -832,13 +832,22 @@ export async function changeInterestStage(
     throw new NotFoundError('Interest');
   }
 
+  // F27: same-stage write is a no-op. Return the existing row without
+  // bumping updatedAt or emitting an audit log entry — pre-fix every
+  // re-submit (e.g. accidental double-click) wrote a "Same → Same"
+  // audit entry and triggered downstream invalidations.
+  if (existing.pipelineStage === data.pipelineStage) {
+    return existing;
+  }
+
   // Plan: yachtId required to leave the initial enquiry stage
   if (
     existing.pipelineStage === 'enquiry' &&
     data.pipelineStage !== 'enquiry' &&
     !existing.yachtId
   ) {
-    throw new ValidationError('yachtId is required before leaving stage=enquiry');
+    // F21: user-readable; was "yachtId is required before leaving stage=enquiry"
+    throw new ValidationError('A yacht must be linked before leaving the Enquiry stage.');
   }
 
   // Block egregious skips. The transition table allows reasonable forward
@@ -848,8 +857,9 @@ export async function changeInterestStage(
   // gates this on the `interests.override_stage` permission and requires
   // a reason, recorded in the audit log below.
   if (!data.override && !canTransitionStage(existing.pipelineStage, data.pipelineStage)) {
+    // F21: use the human-readable stage labels in error copy.
     throw new ValidationError(
-      `Cannot move interest from "${existing.pipelineStage}" directly to "${data.pipelineStage}". Use the override option if you need to skip stages — requires a reason.`,
+      `Cannot move interest from "${STAGE_LABELS[existing.pipelineStage as PipelineStage] ?? existing.pipelineStage}" directly to "${STAGE_LABELS[data.pipelineStage as PipelineStage] ?? data.pipelineStage}". Use the override option if you need to skip stages — requires a reason.`,
     );
   }
   if (data.override && (!data.reason || data.reason.trim().length < 5)) {