fix: replace silent exception handlers with explicit error logging

Every bare `except Exception: pass` or `except Exception: return sentinel`
now logs via logger.exception() or logger.warning() so errors surface in
the application log instead of disappearing silently.

Changes per file:
- admin/routes.py: add logger; log in _inject_admin_sidebar_data(),
  email_detail() Resend enrichment, audiences() contact count loop,
  audience_contacts() Resend fetch
- core.py: log in _get_or_create_resend_audience(), capture_waitlist_email()
  DB insert, and capture_waitlist_email() Resend contact sync (warning level
  since that path is documented as non-critical)
- analytics.py: log DuckDB query failures before returning []

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/padelnomics/admin/routes.py

@@ -2,6 +2,7 @@
 Admin domain: role-based admin panel for managing users, tasks, etc.
 """
 import json
+import logging
 from datetime import date, timedelta
 from pathlib import Path
 
@@ -33,6 +34,8 @@ from ..core import (
     utcnow_iso,
 )
 
+logger = logging.getLogger(__name__)
+
 # Blueprint with its own template folder
 bp = Blueprint(
     "admin",
@@ -50,6 +53,7 @@ async def _inject_admin_sidebar_data():
         row = await fetch_one("SELECT COUNT(*) as cnt FROM inbound_emails WHERE is_read = 0")
         g.admin_unread_count = row["cnt"] if row else 0
     except Exception:
+        logger.exception("Failed to load admin sidebar unread count")
         g.admin_unread_count = 0
 
 
@@ -1041,7 +1045,7 @@ async def email_detail(email_id: int):
             else:
                 enriched_html = getattr(result, "html", "")
         except Exception:
-            pass  # Metadata-only fallback
+            logger.warning("Failed to fetch email body from Resend for %s", email["resend_id"], exc_info=True)
 
     return await render_template(
         "admin/email_detail.html",
@@ -1194,7 +1198,7 @@ async def audiences():
                     data = getattr(contacts, "data", [])
                     a["contact_count"] = len(data) if data else 0
             except Exception:
-                pass
+                logger.warning("Failed to fetch contact count for audience %s", a.get("audience_id"), exc_info=True)
 
     return await render_template("admin/audiences.html", audiences=audience_list)
 
@@ -1220,6 +1224,7 @@ async def audience_contacts(audience_id: str):
             else:
                 contacts = getattr(result, "data", []) or []
         except Exception:
+            logger.exception("Failed to fetch contacts from Resend for audience %s", audience_id)
             await flash("Failed to fetch contacts from Resend.", "error")
 
     return await render_template(

web/src/padelnomics/analytics.py

@@ -10,10 +10,13 @@ Usage:
     rows = await fetch_analytics("SELECT * FROM serving.planner_defaults WHERE city_slug = ?", ["berlin"])
 """
 import asyncio
+import logging
 import os
 from pathlib import Path
 from typing import Any
 
+logger = logging.getLogger(__name__)
+
 _conn = None  # duckdb.DuckDBPyConnection | None — lazy import
 _DUCKDB_PATH = os.environ.get("SERVING_DUCKDB_PATH", "data/analytics.duckdb")
 
@@ -43,7 +46,7 @@ async def fetch_analytics(sql: str, params: list | None = None) -> list[dict[str
     Run a read-only DuckDB query and return rows as dicts.
 
     Returns [] if analytics DB is unavailable (not yet built, or DUCKDB_PATH unset).
-    Never raises — callers should treat empty results as "no data yet".
+    Returns [] on query error after logging — callers treat empty results as "no data yet".
     """
     assert sql, "sql must not be empty"
 
@@ -62,4 +65,5 @@ async def fetch_analytics(sql: str, params: list | None = None) -> list[dict[str
     try:
         return await asyncio.to_thread(_run)
     except Exception:
+        logger.exception("DuckDB analytics query failed: %.200s", sql)
         return []

web/src/padelnomics/core.py

@@ -455,6 +455,7 @@ async def _get_or_create_resend_audience(name: str) -> str | None:
         )
         return audience_id
     except Exception:
+        logger.exception("Failed to create Resend audience %r", name)
         return None
 
 
@@ -495,7 +496,8 @@ async def capture_waitlist_email(
         )
         is_new = cursor_result > 0
     except Exception:
-        # If anything fails, treat as not-new to avoid double-sending
+        logger.exception("Failed to insert waitlist entry for %r", email)
+        # Treat as not-new to avoid double-sending on retry
         is_new = False
 
     # Enqueue confirmation email only if new
@@ -517,7 +519,8 @@ async def capture_waitlist_email(
                 resend.api_key = config.RESEND_API_KEY
                 resend.Contacts.create({"email": email, "audience_id": audience_id})
             except Exception:
-                pass  # Silent fail
+                # Non-critical: audience sync failure doesn't affect waitlist capture
+                logger.warning("Failed to add %r to Resend audience %r", email, audience_name, exc_info=True)
 
     return is_new