fix(librarian): map live HybridRAG response fields correctly

The client parsed field names the live library-desk service never
returns, so every result rendered as "unknown (score: 0.00)":

- source_type/sources -> source + sources (icons key off sources values)
- rrf_score -> score
- context -> formatted_context
- related_dossiers are per-result; top level aggregates unique titles
- synonyms live inside the keywords dict as a {term: [synonyms]} map

Also stop sending zero limits (service 422s on limit < 1); disabled
legs now rely on the enable_* flags with limits clamped to >= 1.

Adds a recorded live response as a fixture plus contract tests that
pin the mapping (non-unknown sources, non-zero scores, icon coverage).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/agents/librarian/tools.py

@@ -9,6 +9,18 @@ from src.core.logging_config import get_logger
 
 logger = get_logger(__name__)
 
+# Icons keyed by the values library-desk emits in each result's `sources`
+# list (search legs) and `source_type` (result origin).
+SOURCE_ICONS = {
+    "vector": "📄",
+    "graph": "🔗",
+    "web": "🌐",
+    "document": "📑",
+    "documents": "📑",
+    "volatile": "⚡",
+    "wiki": "📄",
+}
+
 
 # ============================================================================
 # HybridRAG Search
@@ -76,13 +88,10 @@ async def hybrid_search(
 
             # Add results
             for i, result in enumerate(response.results, 1):
-                source_icon = {
-                    "vector": "📄",
-                    "graph": "🔗",
-                    "web": "🌐",
-                    "document": "📑",
-                    "volatile": "⚡",
-                }.get(result.source, "•")
+                source_keys = result.sources or [result.source]
+                source_icon = "".join(
+                    dict.fromkeys(SOURCE_ICONS.get(key, "•") for key in source_keys)
+                )
 
                 output_parts.append(
                     f"{i}. {source_icon} **{result.title}** (score: {result.score:.2f})"