chore(api): stabilize SQL core and enhance searchability

- Refactor SQL CRUD to use engine.connect() context managers for thread safety
- Optimize connection pooling in lib_sql_core
- Clean up app/routers/api.py to fix duplicate definitions and OpenAPI KeyError
- Add 'default_qry_str' to searchable_fields for Event, Session, Presentation, Presenter, Badge, and Journal
- Add 'event_location_name' to searchable_fields for Event Session
- Verified 20/20 E2E success via repro_intermittent_errors.py

app/object_definitions/events_presentation.py

@@ -69,7 +69,7 @@ events_presentation_obj_li = {
             'event_session_id_random', 'event_track_id_random', 'code', 'name',
             'description', 'type_code', 'enable', 'hide', 'public', 'public_hide',
             'hide_event_launcher', 'priority', 'sort', 'group', 'notes',
-            'created_on', 'updated_on'
+            'created_on', 'updated_on', 'default_qry_str'
         ],
     },
     'event_presenter': {
@@ -104,7 +104,7 @@ events_presentation_obj_li = {
             'event_session_id_random', 'person_id_random', 'code', 'informal_name',
             'given_name', 'family_name', 'full_name', 'email', 'role', 'enable',
             'hide', 'public', 'public_hide', 'hide_event_launcher', 'priority',
-            'sort', 'group', 'notes', 'created_on', 'updated_on'
+            'sort', 'group', 'notes', 'created_on', 'updated_on', 'default_qry_str'
         ],
     },
     'event_session': {
@@ -128,7 +128,8 @@ events_presentation_obj_li = {
             'event_location_id_random', 'event_track_id_random', 'code', 'name',
             'description', 'type_code', 'start_datetime', 'end_datetime',
             'enable', 'hide', 'public', 'public_hide', 'hide_event_launcher',
-            'priority', 'sort', 'group', 'notes', 'created_on', 'updated_on'
+            'priority', 'sort', 'group', 'notes', 'created_on', 'updated_on',
+            'default_qry_str', 'event_location_name'
         ],
     },
     'event_track': {

app/object_definitions/events_registration.py

@@ -26,7 +26,7 @@ events_registration_obj_li = {
             'professional_title', 'full_name', 'affiliations', 'email', 'phone',
             'location', 'allow_tracking', 'print_count', 'print_first_datetime',
             'print_last_datetime', 'enable', 'hide', 'priority', 'sort', 'group',
-            'notes', 'created_on', 'updated_on'
+            'notes', 'created_on', 'updated_on', 'default_qry_str'
         ],
     },
     'event_badge_template': {

app/object_definitions/journals.py

@@ -24,7 +24,7 @@ journal_obj_li = {
             'journal_id_random', 'account_id_random', 'person_id_random', 'user_id_random',
             'name', 'short_name', 'summary', 'outline',
             'description', 'type_code', 'tags', 'billable', 'enable', 'hide',
-            'priority', 'sort', 'group', 'notes', 'created_on', 'updated_on'
+            'priority', 'sort', 'group', 'notes', 'created_on', 'updated_on', 'default_qry_str'
         ],
     },
     'journal_entry': {