feat(inquiries): triage workflow on the inbox (R2-M2)

The inquiry inbox was read-only — every inquiry stayed there forever
with no way to mark "I handled this" or "this is spam." Now:

- Migration 0045 adds triage_state ('open' | 'assigned' | 'converted'
  | 'dismissed' default 'open') + triaged_at + triaged_by columns to
  website_submissions, plus a (port_id, triage_state, received_at)
  index for the inbox query.
- New PATCH /api/v1/admin/website-submissions/[id]/triage flips the
  state with audit log entry.
- List endpoint takes a `state` filter (default 'inbox' = open +
  assigned, hides converted + dismissed).
- UI: per-row Convert / Assign / Dismiss / Reopen actions; second
  filter row for state; triage badge per card. "Convert" jumps to
  /clients with prefill_name / prefill_email / prefill_phone /
  prefill_source / prefill_inquiry_id query params + marks the row
  converted (the client-create form will read those — same prefill
  pattern other entry points use).

1175/1175 vitest passing.

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

src/lib/db/schema/website-submissions.ts

@@ -55,11 +55,21 @@ export const websiteSubmissions = pgTable(
     sourceIp: text('source_ip'),
     userAgent: text('user_agent'),
     receivedAt: timestamp('received_at', { withTimezone: true }).notNull().defaultNow(),
+    /** Triage workflow state. Default 'open'; transitions to
+     *  'converted' (operator created a client/interest from this row),
+     *  'dismissed' (operator marked as not actionable), or 'assigned'
+     *  (operator opened it but hasn't resolved yet). The inbox default
+     *  query filters to open + assigned. */
+    triageState: text('triage_state').notNull().default('open'),
+    triagedAt: timestamp('triaged_at', { withTimezone: true }),
+    /** better-auth user id of the operator who last changed triage_state. */
+    triagedBy: text('triaged_by'),
   },
   (table) => [
     uniqueIndex('idx_ws_submission_id').on(table.submissionId),
     index('idx_ws_port_received').on(table.portId, table.receivedAt),
     index('idx_ws_kind').on(table.kind),
+    index('idx_ws_triage_state').on(table.portId, table.triageState, table.receivedAt),
   ],
 );