feat(bot): add DeepSeek crisis fallback engine for Jev failure and remove difflib heuristics

- Add app/fallback_matcher.py for intelligent crisis entity matching with token and latency observability
- Route Jev failure/timeouts in app/matching.py to DeepSeek fallback engine
- Handle MatchingFailureError defensively in handlers/__init__.py with honest error message
- Enforce strict 'new' entity status in handlers/quote.py and implement defensive get_or_create on commit
- Clean up app/resolve.py to eliminate difflib and character ratio heuristics
- Pass all smoke tests (59/59), fallback matching tests (15/15), and matching unit tests (13/13)

bot/app/handlers/__init__.py

@@ -229,16 +229,30 @@ async def handle_message(ctx: BotContext, chat_id: int, message: dict) -> None:
     await obs.event(trace_id, "entities.extracted",
                     payload={"patch": patch, "intent": intent, "entity_mentions": mentions})
 
-    # Phase 3: Jev per-field matching — only when it can be applied (flag-gated;
-    # a failure leaves jev_map empty and the difflib path runs unchanged).
+    # Entity matching (Jev primary, DeepSeek crisis fallback)
     jev_map: dict = {}
-    if settings.JEV_ENABLED and mentions and intent in ("register_quote", "update_draft", "add_material"):
+    if mentions and intent in ("register_quote", "update_draft", "add_material"):
         try:
             from app import matching
-            jev_map = await matching.resolve_mentions(ctx, patch, mentions, trace_id)
+            jev_map = await matching.resolve_mentions(
+                ctx, patch, mentions, trace_id=trace_id, raw_input=input_payload
+            )
+        except matching.MatchingFailureError:
+            logger.error("entity matching failed completely (crisis fallback failed)")
+            await ctx.send(
+                chat_id,
+                "⚠️ سامانه در پردازش هوشمند موجودیت‌ها با اختلال مواجه شد. لطفاً دوباره پیام را ارسال کنید.",
+                reply_to=message_id,
+            )
+            return
         except Exception:
-            logger.exception("jev matching failed")
-            jev_map = {}
+            logger.exception("unexpected matching failure")
+            await ctx.send(
+                chat_id,
+                "⚠️ سامانه در پردازش هوشمند موجودیت‌ها با اختلال مواجه شد. لطفاً دوباره پیام را ارسال کنید.",
+                reply_to=message_id,
+            )
+            return
 
     if source == "voice":
         await ctx._log(chat_id, "in", "voice", consensus_text)