fix(lint): address errcheck and De Morgan's law violations in doctor/fix

- Handle file.Close() errors in deletions.go and deletions_test.go
- Simplify boolean logic to apply De Morgan's law in common.go
- All golangci-lint checks now pass

cmd/bd/doctor/fix/common.go

@@ -86,5 +86,5 @@ func isWithinWorkspace(root, candidate string) bool {
 	if err != nil {
 		return false
 	}
-	return rel == "." || !(rel == ".." || strings.HasPrefix(rel, ".."+string(os.PathSeparator)))
+	return rel == "." || (rel != ".." && !strings.HasPrefix(rel, ".."+string(os.PathSeparator)))
 }

cmd/bd/doctor/fix/deletions.go

@@ -106,7 +106,9 @@ func getCurrentJSONLIDs(jsonlPath string) (map[string]bool, error) {
 		}
 		return nil, err
 	}
-	defer file.Close()
+	defer func() {
+		_ = file.Close()
+	}()
 
 	scanner := bufio.NewScanner(file)
 	scanner.Buffer(make([]byte, 0, 64*1024), 10*1024*1024)
@@ -161,14 +163,16 @@ func looksLikeIssueID(id string) bool {
 	// Prefix should be alphanumeric (letters/numbers/underscores)
 	prefix := id[:dashIdx]
 	for _, c := range prefix {
-		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_') {
+		isValidPrefixChar := (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_'
+		if !isValidPrefixChar {
 			return false
 		}
 	}
 	// Suffix should be alphanumeric (base36 hash or number), may contain dots for children
 	suffix := id[dashIdx+1:]
 	for _, c := range suffix {
-		if !((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '.') {
+		isValidSuffixChar := (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '.'
+		if !isValidSuffixChar {
 			return false
 		}
 	}

cmd/bd/doctor/fix/deletions_test.go

@@ -47,11 +47,11 @@ func TestGetCurrentJSONLIDs_SkipsTombstones(t *testing.T) {
 	encoder := json.NewEncoder(file)
 	for _, issue := range issues {
 		if err := encoder.Encode(issue); err != nil {
-			file.Close()
+			_ = file.Close()
 			t.Fatalf("Failed to write issue to JSONL: %v", err)
 		}
 	}
-	file.Close()
+	_ = file.Close()
 
 	// Call getCurrentJSONLIDs
 	ids, err := getCurrentJSONLIDs(jsonlPath)