Email search/query + windowed digest preview (v0.1.0:83)

Communications tab (search/query roadmap items 1 & 2):
- Fix the investor dropdown: the facet only listed grid investors, so it
  came back empty whenever email matched a classic contact or org domain
  (no grid id — the common case). It now mirrors the email list, resolving
  each link to a typed identity (fund:/org:/contact:/addr:) with precedence
  grid -> org -> contact -> address; investor_id accepts the typed key
  (bare id = fund: for back-compat) and an unknown prefix matches nothing.
- Add a date-range filter and a click-to-expand full-body view
  (GET /api/email/detail, admin, soft-delete-gated; body_text only, never
  raw remote HTML).
- Add a "Search content" mode: GET /api/email/search wraps the ingest
  hybrid_search over the Qdrant email index (doc_type=email), hydrated and
  soft-delete-filtered against SQLite (canonical), 503 if Spark/Qdrant down.

Daily digest:
- Settings -> Admin builds a digest over a chosen window (last 24h or since
  a date) as an in-app preview before sending (POST /api/admin/digest/preview),
  so the local-Spark summarizer can be verified on demand even on a quiet day.
  Manual send uses the same window; neither advances the daily cursor, so a
  preview never suppresses the scheduled digest.

Code-only, migrations no-op. 22/22 backend tests, render-smoke pass.

backend/server.py

@@ -1914,6 +1914,8 @@ class CRMHandler(BaseHTTPRequestHandler):
             return self.handle_admin_send_test_email(user, body)
         if path == '/api/admin/digest/send-now':
             return self.handle_admin_send_digest_now(user, body)
+        if path == '/api/admin/digest/preview':
+            return self.handle_admin_digest_preview(user, body)
         if path == '/api/fundraising/backup':
             return self.handle_backup_fundraising_state(user)
         if path == '/api/fundraising/restore-preview':
@@ -4140,18 +4142,50 @@ class CRMHandler(BaseHTTPRequestHandler):
 
         return self.send_json({"data": {"status": "sent", **result}})
 
-    def handle_admin_send_digest_now(self, user, body):
-        """Build the REAL daily activity digest (last 24h) on demand and send it to
-        the active-admin set now. An on-demand preview of Phase B — it does not
-        touch the daily schedule's cursor, so it never suppresses the scheduled send.
-        Content is summarized on Spark (local), never Claude."""
+    def handle_admin_digest_preview(self, user, body):
+        """Build the activity digest over a chosen window and return it WITHOUT
+        sending — the admin-panel preview. Window defaults to the last 24h, or
+        {hours: N} / {since: 'YYYY-MM-DD'} (a local date -> that day's midnight).
+        Runs the REAL Spark summarization, so widening the window is how you verify
+        the summarizer on a quiet day. Never touches the daily cursor."""
         if not require_admin(user):
             return self.send_error_json("Admin only", 403)
-
-        import digest_mailer
+        body = body or {}
+        import digest_builder
         try:
-            from email_integration.digest_scheduler import maybe_send_digest
-            result = maybe_send_digest(force=True)
+            since_iso, until_iso = digest_builder.resolve_digest_window(
+                hours=body.get('hours'), since=body.get('since'))
+        except ValueError as exc:
+            return self.send_error_json(str(exc), 400)
+        conn = get_db()
+        try:
+            digest = digest_builder.build_digest(conn, since_iso, until_iso)
+        except Exception as exc:
+            print(f"[digest] preview failed: {type(exc).__name__}: {exc}", file=sys.stderr)
+            return self.send_error_json("Preview failed — see server logs for details.", 502)
+        finally:
+            conn.close()
+        return self.send_json({"data": {**digest, "window": [since_iso, until_iso]}})
+
+    def handle_admin_send_digest_now(self, user, body):
+        """Build the REAL activity digest over a chosen window and send it to the
+        active-admin set now. Window defaults to the last 24h, or {hours: N} /
+        {since: 'YYYY-MM-DD'} — same resolution as the preview. Does NOT touch the
+        daily schedule's cursor, so it never suppresses the scheduled send. Content
+        is summarized on Spark (local), never Claude."""
+        if not require_admin(user):
+            return self.send_error_json("Admin only", 403)
+        body = body or {}
+        import digest_mailer
+        import digest_builder
+        try:
+            since_iso, until_iso = digest_builder.resolve_digest_window(
+                hours=body.get('hours'), since=body.get('since'))
+        except ValueError as exc:
+            return self.send_error_json(str(exc), 400)
+        try:
+            from email_integration.digest_scheduler import send_digest_window
+            result = send_digest_window(since_iso=since_iso, until_iso=until_iso)
         except digest_mailer.NoTransport as exc:
             return self.send_error_json(str(exc), 400)
         except Exception as exc: