Migrate configuration from environment variables to YAML file

- Add YAML-based configuration loaded from config.yaml (CONFIG_LOCATION env var)
  - Add PyYAML dependency and install requirements in Dockerfile
  - Replace Config.from_env() with get_config() singleton pattern
  - Remove server_header from config (now randomized from wordlists only)
  - Update docker-compose.yaml to mount config.yaml read-only
  - Update Helm chart: restructure values.yaml, generate config.yaml in ConfigMap
  - Update Kubernetes manifests: ConfigMap now contains config.yaml, deployments mount it
  - Remove Helm secret.yaml (dashboard path now auto-generated in config.yaml)

kubernetes/manifests/deployment.yaml

@@ -23,10 +23,14 @@ spec:
         - containerPort: 5000
           name: http
           protocol: TCP
-        envFrom:
-        - configMapRef:
-            name: krawl-config
+        env:
+        - name: CONFIG_LOCATION
+          value: "config.yaml"
         volumeMounts:
+        - name: config
+          mountPath: /app/config.yaml
+          subPath: config.yaml
+          readOnly: true
         - name: wordlists
           mountPath: /app/wordlists.json
           subPath: wordlists.json
@@ -41,6 +45,9 @@ spec:
             memory: "256Mi"
             cpu: "500m"
       volumes:
+      - name: config
+        configMap:
+          name: krawl-config
       - name: wordlists
         configMap:
           name: krawl-wordlists