feat(ux): unify "Ask Claude to Edit" + inline prompt at selection; fix keybindings

Operator feedback on the Ask-Claude ergonomics (relates to #42/#43/#60):

- One user-facing command `cowriting.edit` ("Ask Claude to Edit") routes to the
  selection or whole-document flow at runtime via the pure `routeEdit` helper
  (selection → editSelection; none / tab right-click → editDocument). The two
  underlying commands stay registered for the seams + E2E but are hidden from the
  palette, and the split menu pairs collapse to one entry.
- Keybindings with `mac` variants (the missing variant is why ⌃⌥R "didn't work"
  on macOS — Option combos are unreliable there): `cmd+alt+e`/`ctrl+alt+e` for
  Ask-Claude-to-Edit, `cmd+alt+r`/`ctrl+alt+r` for the review panel.
- The instruction prompt now renders INLINE at the selection/cursor via a
  dedicated Comments-API controller (`InlineAskController`, `cowriting.askClaude`)
  instead of the top-center QuickInput — VS Code's Inline-Chat-style placement.
  Both Ask-Claude entry points (editSelection + the preview's askClaude) share it.

Tests: routeEdit unit tests; E2E menu/palette assertions updated for the unified
command; E2E drives the inline prompt by stubbing `api.inlineAsk.prompt`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test/workspacePath.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { isAuthorable, isUnderRoot, selectionRejection } from "../src/workspacePath";
+import { isAuthorable, isUnderRoot, routeEdit, selectionRejection } from "../src/workspacePath";
 
 describe("isUnderRoot", () => {
   const root = "/a/vscode-cowriting-plugin/sandbox";
@@ -58,3 +58,27 @@ describe("selectionRejection — F8 widened (accepts out-of-folder + untitled)",
     expect(msg).not.toMatch(/select some text/i);
   });
 });
+
+describe("routeEdit (single Ask-Claude-to-Edit gesture)", () => {
+  const focused = { hasUri: false, uriMatchesActiveEditor: false, hasActiveEditor: true, selectionEmpty: false };
+
+  it("non-empty selection in the focused editor → selection", () => {
+    expect(routeEdit(focused)).toBe("selection");
+  });
+  it("empty selection in the focused editor → document", () => {
+    expect(routeEdit({ ...focused, selectionEmpty: true })).toBe("document");
+  });
+  it("no active editor → document", () => {
+    expect(routeEdit({ ...focused, hasActiveEditor: false, selectionEmpty: true })).toBe("document");
+  });
+  it("tab right-click on a doc that ISN'T the focused editor → document (no selection to act on)", () => {
+    expect(routeEdit({ hasUri: true, uriMatchesActiveEditor: false, hasActiveEditor: true, selectionEmpty: false })).toBe(
+      "document",
+    );
+  });
+  it("tab right-click on the focused editor with a selection → selection", () => {
+    expect(routeEdit({ hasUri: true, uriMatchesActiveEditor: true, hasActiveEditor: true, selectionEmpty: false })).toBe(
+      "selection",
+    );
+  });
+});