fix: remove pool-nuking reconnect_db() from OperationalError retry paths

On OperationalError, sql_update and run_sql_select were calling
sql_connect() → reconnect_db() which disposes the entire connection
pool mid-flight, killing other in-flight connections under concurrency.

Removed the sql_connect() calls; the existing retry blocks already open
a fresh engine.connect() context manager, and pool_pre_ping=True handles
stale connection detection. Also drops the now-unused sql_connect import.

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

app/lib_sql_crud.py

@@ -11,7 +11,7 @@ from sqlalchemy.exc import IntegrityError, OperationalError, ProgrammingError
 from app.log import log, logger_reset
 # CRITICAL: Import the core module to access current global state
 from app import lib_sql_core
-from app.lib_sql_core import sql_connect, set_last_sql_error
+from app.lib_sql_core import set_last_sql_error
 
 # log.setLevel(logging.DEBUG) # DEBUG, INFO, WARNING, ERROR, EXCEPTION, CRITICAL
 
@@ -138,7 +138,6 @@ def sql_update(
     except OperationalError:
         if trans: trans.rollback()
         log.error('Operational error (gone away?). Retrying once...')
-        sql_connect()
         try:
             with lib_sql_core.engine.connect() as conn:
                 trans = conn.begin()
@@ -343,7 +342,6 @@ def run_sql_select(
             return conn.execute(sql, data)
     except (OperationalError, ProgrammingError) as e:
         log.error(f'DB Error: {e}. Retrying once...')
-        sql_connect()
         try:
             with lib_sql_core.engine.connect() as conn:
                 return conn.execute(sql, data)