feat(brain): audit-log every tools/call; server-owned write provenance (#147)

Closes #144 (audit line per tools/call) and #145 (origin/written_by stamped on every model-reachable write, surfaced in brain_query/brain_get).

Passed pr-gatekeeper after four rounds of adversarial review, verified by execution: #147

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Mathias <mthbqv@gmail.com>

ingestion/internal/api/promote.go

@@ -72,6 +72,10 @@ type PromoteOptions struct {
 	Wing     string
 	Hall     string
 	Slug     string // optional; defaults to Filename minus date prefix + .md
+	// Origin/WrittenBy re-attribute the promoted note to the promoter: the raw
+	// note's own frontmatter claims are not provenance (hyperguild#145).
+	Origin    string
+	WrittenBy string
 }
 
 // PromoteNote moves a note from brain/raw/ into the structured wiki: it
@@ -128,7 +132,11 @@ func PromoteNote(brainDir string, opts PromoteOptions) (string, error) {
 		return "", fmt.Errorf("create wing dir: %w", err)
 	}
 	// Write-then-delete: the source survives any write failure.
-	if err := os.WriteFile(dest, []byte(fm.render()+body), 0o644); err != nil {
+	promoted, err := StampProvenance(fm.render()+body, opts.Origin, opts.WrittenBy)
+	if err != nil {
+		return "", err
+	}
+	if err := os.WriteFile(dest, []byte(promoted), 0o644); err != nil {
 		return "", fmt.Errorf("write promoted note: %w", err)
 	}
 	if err := os.Remove(src); err != nil {