Second-pass review fixes: kill last hardcoded creds, wire get_services, dedup

Verification audit (re-run of the 6 skill lenses) confirmed the prior fixes hold
and surfaced a few misses:

Security (HIGH):
- search.py _check_smart_redirect still opened a raw pymysql connection with
  root/rootpassword (reachable on any 9-digit SSO query). Now uses the shared
  env-backed employee_connection helper.
- Deleted dead shopdb/core/services/employee_service.py (zero importers; carried
  another root/rootpassword literal). No hardcoded credentials remain in app
  logic; config.py dev defaults stay gated by ProductionConfig.validate.

Dead hook:
- get_services was implemented by the printers plugin but had no consumer (docs
  claimed otherwise). Added PluginManager.get_service(name) that resolves a
  service from enabled plugins; updated PLUGIN-HOOKS.md.

Tests:
- search disabled-plugin exclusion (the high-value gap): enabled plugin's
  hostname appears, disabled plugin's hostname drops out (searched by a hostname
  distinct from assetnumber so only the gated domain can match).
- get_service consumer test (unknown name -> None).

Simplify:
- Extract the triplicated GE_LOGO_SVG + loadLogo + drawLogoOverlay into shared
  frontend/src/views/print/qrLogo.js (renderQrDataUrl); both QR views use it.
- applications.py: lift the misplaced pagination import to the top; drop unused
  Computer unpacking in the 3 endpoints that only touch ComputerInstalledApp.

154 tests pass, naming/style green, app boots, QR render verified.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

shopdb/core/api/search.py

@@ -522,14 +522,9 @@ def _check_smart_redirect(query, classification):
     # Exact SSO match
     if classification['is_sso']:
         try:
-            import pymysql
-            emp_conn = pymysql.connect(
-                host='localhost',
-                user='root',
-                password='rootpassword',
-                database='wjf_employees',
-                cursorclass=pymysql.cursors.DictCursor
-            )
+            # Shared env-backed connection helper; never hardcode creds.
+            from shopdb.utils.employee_db import employee_connection
+            emp_conn = employee_connection()
             with emp_conn.cursor() as cur:
                 cur.execute(
                     'SELECT SSO, First_Name, Last_Name FROM employees WHERE SSO = %s LIMIT 1',