Migrate golangci-lint configuration to v2 schema

- Convert configuration to golangci-lint v2 format
- Use version: "2" (string format as required)
- Replace disable-all/enable-all with linters.default: false
- Move gofmt/goimports to formatters section
- Keep all existing linter settings and exclusions
- This resolves configuration validation errors in CI

Author: vnykmshr

.golangci.yml

@@ -1,9 +1,37 @@
-version: 2
+version: "2"
 
 run:
   timeout: 5m
   modules-download-mode: readonly
 
+output:
+  formats:
+    - format: colored-line-number
+      path: stdout
+
+linters:
+  default: false
+  enable:
+    - errcheck
+    - gosimple
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - goconst
+    - gocyclo
+    - gosec
+    - misspell
+    - unconvert
+    - unparam
+    - gocritic
+    - revive
+
+formatters:
+  enable:
+    - gofmt
+    - goimports
+
 linters-settings:
   errcheck:
     check-type-assertions: true
@@ -24,83 +52,63 @@ linters-settings:
     simplify: true
   gosec:
     excludes:
-      - G404 # Use of weak random number generator is acceptable for cache keys
-
-linters:
-  disable-all: true
-  enable:
-    - errcheck
-    - gosimple
-    - govet
-    - ineffassign
-    - staticcheck
-    - unused
-    - goconst
-    - gocyclo
-    - gofmt
-    - goimports
-    - gosec
-    - misspell
-    - unconvert
-    - unparam
-    - gocritic
-    - revive
+      - G404
 
 issues:
   exclude-rules:
     - path: _test\.go
       linters:
         - gosec
         - gocritic
-        - errcheck  # Test files often don't need to check all errors
-        - goconst   # Test files often have repeated strings
-        - unparam   # Test functions often have unused params
-        - revive    # Test files often have complex structures
-        - gocyclo   # Test functions can be complex
+        - errcheck
+        - goconst
+        - unparam
+        - revive
+        - gocyclo
     - path: bench_test\.go
       linters:
-        - errcheck  # Benchmark files focus on performance, not error handling
-        - unparam   # Benchmark functions often have unused params
+        - errcheck
+        - unparam
     - path: examples/
       linters:
         - gosec
         - gocritic
     - path: internal/singleflight/
       linters:
-        - revive # Allow non-standard error position for singleflight API compatibility
+        - revive
     - path: pkg/obcache/wrap\.go
       linters:
-        - errcheck  # Complex reflection code needs some unchecked errors
-        - revive    # Allow complex if-else structure for reflection logic
+        - errcheck
+        - revive
     - path: internal/store/memory/memory\.go
       linters:
-        - goimports # Allow alias import for LRU library
+        - goimports
     - path: internal/eviction/
       linters:
-        - revive    # Allow EvictionType naming
-        - goimports # Allow alias import for LRU library
+        - revive
+        - goimports
     - path: internal/store/redis/redis\.go
       linters:
-        - errcheck  # Redis operations may have ignored errors for performance
-        - revive    # Allow certain code patterns for Redis integration
+        - errcheck
+        - revive
     - path: pkg/obcache/logging\.go
       linters:
-        - revive     # Allow empty blocks in example code
-        - staticcheck # Allow empty branches in example code
+        - revive
+        - staticcheck
     - text: "SA1029.*should not use built-in type string as key"
       linters:
-        - staticcheck # Allow string keys in context for testing/examples
+        - staticcheck
     - text: "SA9003.*empty branch"
       linters:
-        - staticcheck # Allow empty branches in example code
+        - staticcheck
     - path: pkg/obcache/logging_test.go
       linters:
-        - staticcheck # Test code may have intentional nil checks
+        - staticcheck
     - text: "unused-parameter.*seems to be unused"
       linters:
-        - revive # Allow unused parameters in interface implementations
+        - revive
     - text: "result.*is always nil"
       linters:
-        - unparam # Allow methods that always return nil for interface compliance
+        - unparam
   max-issues-per-linter: 0
   max-same-issues: 0