fix(ci): add version: 2 to .golangci.yml for v2.x compatibility

- Add explicit 'version: 2' field at top of config
- Required by golangci-lint v2.7.2
- Update compatibility comment v1.64+ → v2.7.2

Error fixed:
  unsupported version of the configuration: ""

v2.x requires explicit version declaration in config file

Related: Story 5 CI/CD Pipeline

Author: chendelin1982

core/.golangci.yml

@@ -1,7 +1,10 @@
 # golangci-lint configuration for apprun project
-# Compatible with golangci-lint v1.64+
+# Compatible with golangci-lint v2.7.2
 # Documentation: https://golangci-lint.run/usage/configuration/
 
+# Version declaration for v2.x (required)
+version: 2
+
 run:
   timeout: 5m
   tests: true