fix(ci): migrate to golangci-lint v2, fix lint violations

golangci-lint-action >= v7 only supports v2.x. v2 requires:
- version: "2" at top of .golangci.yml
- gosimple removed (merged into staticcheck in v2)

Also fix the 4 issues v2 surfaced:
- defer resp.Body.Close() / f.Close(): add //nolint:errcheck (idiomatic
  Go, errors from deferred closes cannot be meaningfully handled)
- pkg/embedding/cohere: lowercase error string (ST1005)

Co-authored-by: Ona <no-reply@ona.com>

Author: Siddhant-K-code

.github/workflows/ci.yml

@@ -39,4 +39,4 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@1e7e51e771db61008b38414a730f564565cf7c20 # v9.2.0
         with:
-          version: v1.64.8
+          version: v2.1.6

.golangci.yml

@@ -1,20 +1,16 @@
+version: "2"
+
 linters:
+  default: none
   enable:
     - errcheck
-    - gosimple
     - govet
     - ineffassign
     - staticcheck
     - unused
 
-linters-settings:
-  errcheck:
-    check-type-assertions: false
-    check-blank: false
-
 issues:
   exclude-rules:
-    # Test files: allow unchecked errors on t.Log, t.Error etc.
     - path: _test\.go
       linters:
         - errcheck

pkg/embedding/cohere/client.go

@@ -61,7 +61,7 @@ type Client struct {
 // NewClient creates a new Cohere embedding client.
 func NewClient(cfg Config) (*Client, error) {
 	if cfg.APIKey == "" {
-		return nil, fmt.Errorf("Cohere API key is required")
+		return nil, fmt.Errorf("cohere API key is required")
 	}
 	if cfg.Model == "" {
 		cfg.Model = defaultModel
@@ -129,7 +129,7 @@ func (c *Client) EmbedBatch(ctx context.Context, texts []string) ([][]float32, e
 	if err != nil {
 		return nil, fmt.Errorf("cohere request: %w", err)
 	}
-	defer resp.Body.Close()
+	defer resp.Body.Close() //nolint:errcheck
 
 	if resp.StatusCode == http.StatusTooManyRequests {
 		return nil, embedding.ErrRateLimited

pkg/embedding/ollama/client.go

@@ -85,7 +85,7 @@ func (c *Client) Embed(ctx context.Context, text string) ([]float32, error) {
 	if err != nil {
 		return nil, fmt.Errorf("ollama request: %w", err)
 	}
-	defer resp.Body.Close()
+	defer resp.Body.Close() //nolint:errcheck
 
 	if resp.StatusCode != http.StatusOK {
 		b, _ := io.ReadAll(resp.Body)

pkg/graph/builder.go

@@ -80,7 +80,7 @@ func parseGoImports(path string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
+	defer f.Close() //nolint:errcheck
 
 	var imports []string
 	scanner := bufio.NewScanner(f)