feat(linter): add file/line to findings; downgrade extends missing-script to warning

Every finding now carries the source file and exact line number of the job
key in its YAML file. Format: [ERROR] job "name" (file.yml:12): message.

Pipeline-level findings (workflow rules, no stages) reference p.SourceFile.
Cross-file include jobs (local, project, component) carry the include source
as their File, set via Pipeline.SetJobOrigin after each ParseBytes call in
the resolver.

Line numbers come from the yaml.Node key node (exact job-name line) in a
new document-level first pass in ParseBytes, replacing the previous
map[string]yaml.Node approach which only gave value-node lines.

Also: jobs that declare extends: but have no script after resolution now
emit WARNING instead of ERROR. The script may come from a base in a remote
include that was not fetched (no token, offline), making the error a false
positive in common project setups.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/model/parser.go

@@ -13,14 +13,22 @@ func Parse(path string) (*Pipeline, error) {
 	if err != nil {
 		return nil, fmt.Errorf("reading file: %w", err)
 	}
-	return ParseBytes(data)
+	p, err := ParseBytes(data)
+	if err != nil {
+		return nil, err
+	}
+	p.SourceFile = path
+	p.SetJobOrigin(path)
+	return p, nil
 }
 
 // ParseBytes parses YAML from an in-memory byte slice.
 func ParseBytes(data []byte) (*Pipeline, error) {
-	// First pass: decode into a raw map to extract job keys.
-	var raw map[string]yaml.Node
-	if err := yaml.Unmarshal(data, &raw); err != nil {
+	// First pass: parse into a yaml.Node document to extract job keys with
+	// their exact source line numbers (key nodes carry the line, value nodes
+	// carry the body we decode into Job / map[string]any).
+	var doc yaml.Node
+	if err := yaml.Unmarshal(data, &doc); err != nil {
 		return nil, fmt.Errorf("parsing YAML: %w", err)
 	}
 
@@ -32,21 +40,36 @@ func ParseBytes(data []byte) (*Pipeline, error) {
 
 	p.Jobs = make(map[string]Job)
 	p.RawJobs = make(map[string]map[string]any)
-	for key, node := range raw {
+
+	if doc.Kind != yaml.DocumentNode || len(doc.Content) == 0 {
+		return p, nil
+	}
+	root := doc.Content[0]
+	if root.Kind != yaml.MappingNode {
+		return p, nil
+	}
+
+	// Walk root mapping in key/value pairs.
+	for i := 0; i+1 < len(root.Content); i += 2 {
+		keyNode := root.Content[i]
+		valNode := root.Content[i+1]
+		key := keyNode.Value
 		if ReservedKeys[key] {
 			continue
 		}
+
 		var rawMap map[string]any
-		if err := node.Decode(&rawMap); err != nil {
+		if err := valNode.Decode(&rawMap); err != nil {
 			return nil, fmt.Errorf("parsing raw job %q: %w", key, err)
 		}
 		p.RawJobs[key] = rawMap
 
 		var j Job
-		if err := node.Decode(&j); err != nil {
+		if err := valNode.Decode(&j); err != nil {
 			return nil, fmt.Errorf("parsing job %q: %w", key, err)
 		}
 		j.Name = key
+		j.Line = keyNode.Line // exact line of the job name key
 		p.Jobs[key] = j
 	}