Fix/pylint cleanup (#8)

* Fix pylint warnings across all 24 Python files in web_server

- Add module, class, and function docstrings (C0114, C0115, C0116)
- Fix import ordering: stdlib before third-party before local (C0411)
- Replace wildcard imports with explicit named imports (W0401)
- Remove trailing whitespace and add missing final newlines (C0303, C0304)
- Replace dict() with dict literals (R1735)
- Remove unused imports and variables (W0611, W0612)
- Narrow broad Exception catches to specific exceptions (W0718)
- Replace f-string logging with lazy % formatting (W1203)
- Fix variable naming: UPPER_CASE for constants, snake_case for locals (C0103)
- Add pylint disable comments for necessary global statements (W0603)
- Fix no-else-return, simplifiable-if-expression, singleton-comparison
- Fix bad indentation in stripe.py (W0311)
- Add encoding="utf-8" to open() calls (W1514)
- Add check=True to subprocess.run() calls (W1510)
- Register Celery task modules via conf.include

* Update `package-lock.json` add peer dependencies

web_server/database/database.py

@@ -1,7 +1,12 @@
+"""SQLite database connection management with context manager support."""
+
 import sqlite3
 import os
 
+
 class Database:
+    """Database wrapper providing connection management and query execution."""
+
     def __init__(self) -> None:
         self._db = os.path.join(os.path.abspath(os.path.dirname(__file__)), "app.db")
         self._conn = None
@@ -63,4 +68,6 @@ class Database:
         if not result:
             return []
         columns = [desc[0] for desc in self.cursor.description]
-        return [dict(zip(columns, row)) for row in result] if isinstance(result, list) else dict(zip(columns, result))
+        if isinstance(result, list):
+            return [dict(zip(columns, row)) for row in result]
+        return dict(zip(columns, result))