Fix golangci-lint: formatting, nilerr false positive, deprecated linter names

- gofmt: fix struct field alignment in types.go, resource_server.go,
  data_source_ssh_keys_by_user.go
- nilerr: refactor GetAllPages pagination detection to avoid returning
  nil error when json.Unmarshal fails (intentional passthrough for
  non-paginated responses)
- .golangci.yml: replace deprecated linter names (vet -> govet,
  tenv -> usetesting)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.golangci.yml

@@ -16,8 +16,8 @@ linters:
     - nilerr
     - predeclared
     - staticcheck
-    - tenv
+    - usetesting
     - unconvert
     - unparam
     - unused
-    - vet
+    - govet

internal/client/request.go

@@ -37,8 +37,11 @@ func (c *Client) GetAllPages(ctx context.Context, path string) (json.RawMessage,
 	}
 
 	var page paginatedResponse
-	if err := json.Unmarshal(firstRaw, &page); err != nil || page.LastPage == 0 {
-		// Not a paginated response — return as-is.
+	// Attempt to detect pagination metadata. If the response doesn't look
+	// like a paginated envelope (unmarshal fails or last_page is absent/zero),
+	// return the raw response as-is — this is not an error.
+	unmarshallable := json.Unmarshal(firstRaw, &page) == nil
+	if !unmarshallable || page.LastPage <= 1 {
 		return firstRaw, nil
 	}