fix: golangci-lint config v1 format for compatibility

Changes:
- Remove version: "2" (not needed and causes issues)
- Rename linters.settings → linters-settings (v1 format)
- Remove issues.exclude-rules (use simple exclude list)
- Remove errcheck.exclude-files (not supported in v2.5.0)

This fixes config validation errors:
- "additional properties 'exclude-rules' not allowed"
- "additional properties 'exclude-files' not allowed"

.golangci.yml

@@ -1,5 +1,3 @@
-version: "2"
-
 run:
   timeout: 5m
   tests: true
@@ -16,14 +14,13 @@ linters:
     - misspell
     - unconvert
     - unparam
-  settings:
+
+linters-settings:
   dupl:
     threshold: 100
   errcheck:
     check-type-assertions: false
     check-blank: false
-      exclude-files:
-        - ".*_test\\.go$"
     exclude-functions:
       - (*database/sql.DB).Close
       - (*database/sql.Rows).Close
@@ -41,19 +38,11 @@ linters:
       - name: exported
 
 issues:
-  exclude-rules:
+  exclude:
-    - path: _test\.go
+    - "var-naming: avoid meaningless package names"
-      linters:
+    - "exported.*SQLiteStorage.*stutters"
-        - gosec
+    - "G201: SQL string formatting"
-        - revive
+    - "G301: Expect directory permissions"
-    - text: "var-naming: avoid meaningless package names"
+    - "G204: Subprocess launched"
-    - text: "exported.*SQLiteStorage.*stutters"
+    - "G115: integer overflow conversion"
-    - text: "G201: SQL string formatting"
+    - "G304.*file inclusion via variable"
-    - text: "G301: Expect directory permissions"
-    - text: "G204: Subprocess launched"
-    - text: "G115: integer overflow conversion"
-    - text: "G304.*file inclusion via variable"
-    - path: (export|sync|init)\.go
-      text: "G302|G306.*0644"
-    - path: server\.go
-      text: "G302"