Add 6 new tools: Hasher, Base64, JWT Decoder, Password Gen, Timestamp, Text Diff

- backend/tools/hasher.py: POST /api/hash/sha256 and /api/hash/bcrypt (bcrypt added to requirements)
- backend/tools/base64tool.py: POST /api/base64/encode and /api/base64/decode
- backend/tools/jwtdecoder.py: POST /api/jwt/decode (signature verification disabled)
- backend/tools/passwordgen.py: POST /api/password/generate with charset and length options
- backend/tools/timestamp.py: POST /api/timestamp/convert (unix<->date, ISO 8601 + German format)
- backend/tools/textdiff.py: POST /api/text/diff returning structured added/removed/unchanged lines
- All blueprints registered in app.py and tools/__init__.py
- React components with copy button, dark/light mode support via CSS variables
- ToolOverview rebuilt as card grid; App.jsx routes added for all tools

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

backend/app.py

@@ -10,7 +10,15 @@ from util.db_config import is_configured, load_config, test_connection
 from util.setup_routes import setup_blueprint
 from util.limiter import limiter
 from auth import auth_bp
-from tools import md5_blueprint
+from tools import (
+    md5_blueprint,
+    hasher_blueprint,
+    base64_blueprint,
+    jwt_decoder_blueprint,
+    passwordgen_blueprint,
+    timestamp_blueprint,
+    textdiff_blueprint,
+)
 from admin import admin_bp
 
 app = Flask(__name__, template_folder="templates")
@@ -20,6 +28,12 @@ limiter.init_app(app)
 app.register_blueprint(setup_blueprint)
 app.register_blueprint(auth_bp)
 app.register_blueprint(md5_blueprint)
+app.register_blueprint(hasher_blueprint)
+app.register_blueprint(base64_blueprint)
+app.register_blueprint(jwt_decoder_blueprint)
+app.register_blueprint(passwordgen_blueprint)
+app.register_blueprint(timestamp_blueprint)
+app.register_blueprint(textdiff_blueprint)
 app.register_blueprint(admin_bp)
 
 # 🌐 React-Frontend ausliefern