feat: currentAuthor() carries git user.email — fail-open identity (F5 SLICE-2, #14)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/attributionController.ts

@@ -13,6 +13,7 @@ import * as vscode from "vscode";
 import { CoauthorStore } from "./store";
 import { newId, type AttributionRecord, type Provenance } from "./model";
 import { buildFingerprint, resolve, type OffsetRange } from "./anchorer";
+import { gitUserEmail } from "./identity";
 import { applyChange, coalesce, type LiveSpan } from "./attributionTracker";
 import { minimizeReplace, PendingEditRegistry } from "./pendingEdits";
 
@@ -79,7 +80,8 @@ export class AttributionController implements vscode.Disposable {
   }
   private currentAuthor(): Provenance {
     const id = vscode.workspace.getConfiguration("git").get<string>("user.name") || process.env.USER || "human";
-    return { kind: "human", id };
+    const email = gitUserEmail(this.rootDir);
+    return { kind: "human", id, ...(email !== undefined ? { email } : {}) };
   }
   private state(docPath: string): DocAttribution {
     let s = this.docs.get(docPath);