feat(digests-ui): publication filter + 'מאמר'/source badges for bulletins

משלים את #154 בצד-לקוח:
- פילטר "מקור" בדף /digests (כל המקורות / כל יום / עו"ד על נדל"ן) — backend:
  list_digests + /api/digests מקבלים publication.
- DigestCard: תג "מאמר" ל-digest_kind='article', ו-chip מקור לפרסום שאינו 'כל יום'.

build (webpack) עובר, lint נקי. digests = hand-written types (אין api:types).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mcp-server/src/legal_mcp/services/db.py

@@ -3800,11 +3800,13 @@ async def list_digests(
     concept_tag: str = "",
     linked: bool | None = None,
     search: str = "",
+    publication: str = "",
     limit: int = 100,
     offset: int = 0,
 ) -> list[dict]:
     """List digests with simple filters. linked=True/False filters on whether
-    the underlying ruling is in the library yet (INV-DIG3 gap surfacing)."""
+    the underlying ruling is in the library yet (INV-DIG3 gap surfacing).
+    publication filters the source ('כל יום' daily vs 'עו"ד על נדל"ן' monthly)."""
     pool = await get_pool()
     conditions: list[str] = []
     params: list = []
@@ -3813,6 +3815,10 @@ async def list_digests(
         conditions.append(f"practice_area = ${idx}")
         params.append(practice_area)
         idx += 1
+    if publication:
+        conditions.append(f"publication = ${idx}")
+        params.append(publication)
+        idx += 1
     if concept_tag:
         conditions.append(f"concept_tag ILIKE ${idx}")
         params.append(f"%{concept_tag}%")

mcp-server/src/legal_mcp/services/digest_library.py

@@ -404,12 +404,13 @@ async def list_digests(
     concept_tag: str = "",
     linked: bool | None = None,
     search: str = "",
+    publication: str = "",
     limit: int = 100,
     offset: int = 0,
 ) -> list[dict]:
     return await db.list_digests(
         practice_area=practice_area, concept_tag=concept_tag, linked=linked,
-        search=search, limit=limit, offset=offset,
+        search=search, publication=publication, limit=limit, offset=offset,
     )