feat(app): unify composer attachments with pill + lightbox redesign

Images and GitHub issues/PRs now live in one draft-store list (ComposerAttachment union) with cwd persisted on the draft. Paperclip becomes a + drop-up menu; queue button removed. Each pill uses a shared AttachmentPill wrapper with a corner-X that mirrors the auto-update toast spec. Pill body opens the attachment: GitHub via openExternalUrl, images via a new fullscreen AttachmentLightbox. GitHub picker auto-closes on select.

packages/app/src/stores/draft-store.lifecycle.test.ts

@@ -7,19 +7,19 @@ describe("draft-store lifecycle", () => {
     const nowMs = 1_000_000;
     const drafts = {
       oldSent: {
-        input: { text: "", images: [] },
+        input: { text: "", attachments: [], cwd: "" },
         lifecycle: "sent" as const,
         updatedAt: 0,
         version: 2,
       },
       recentAbandoned: {
-        input: { text: "", images: [] },
+        input: { text: "", attachments: [], cwd: "" },
         lifecycle: "abandoned" as const,
         updatedAt: nowMs + 2 * 60 * 1000,
         version: 2,
       },
       active: {
-        input: { text: "a", images: [] },
+        input: { text: "a", attachments: [], cwd: "/repo" },
         lifecycle: "active" as const,
         updatedAt: 0,
         version: 1,
@@ -41,15 +41,19 @@ describe("draft-store lifecycle", () => {
       record: {
         input: {
           text: "hello",
-          images: [
+          attachments: [
             {
-              id: "att-1",
-              mimeType: "image/jpeg",
-              storageType: "web-indexeddb",
-              storageKey: "att-1",
-              createdAt: 1,
+              kind: "image",
+              metadata: {
+                id: "att-1",
+                mimeType: "image/jpeg",
+                storageType: "web-indexeddb",
+                storageKey: "att-1",
+                createdAt: 1,
+              },
             },
           ],
+          cwd: "/repo",
         },
         lifecycle: "active",
         updatedAt: 1,
@@ -60,7 +64,7 @@ describe("draft-store lifecycle", () => {
     });
 
     expect(cleared).toEqual({
-      input: { text: "", images: [] },
+      input: { text: "", attachments: [], cwd: "" },
       lifecycle: "sent",
       updatedAt: 2,
       version: 2,