feat(checkout): merge PR action with real-GitHub e2e test (#814)

* feat(checkout): merge PR action with real-GitHub e2e test

Adds a `checkoutPrMerge` server RPC backed by `gh pr merge` (squash, merge,
or rebase) and surfaces three new actions in the git-actions menu —
"Squash and merge", "Create a merge commit", "Rebase and merge" — with
squash taking the primary slot when a PR is open and mergeable. Also
renames the existing local merge action to "Merge locally" to disambiguate
it from the new GitHub-side merge.

Adds an end-to-end test that creates a real temporary GitHub repo, opens a
PR via the daemon, polls until mergeable, calls `checkoutPrMerge`, and
verifies the merge landed on `main` — no mocks. The test pre-flights the
`delete_repo` scope so it skips cleanly on tokens that can't tear down,
and fails loud if cleanup ever errors so we don't leak repos.

PR status gains an optional `mergeable` field (`MERGEABLE | CONFLICTING |
UNKNOWN`) populated from `gh pr view --json mergeable`. The schema is
backward compatible — old payloads without the field still parse and
default to `UNKNOWN` via `z.catch`.

* Update PR status snapshot expectations

* refactor: collect git/checkout/PR feature into packages/app/src/git/

Move 21 git/checkout/PR files out of components/, hooks/, stores/, screens/,
utils/ flat-peer slop into a single packages/app/src/git/ module with
shrunk filenames (git-diff-pane.tsx -> diff-pane.tsx, use-git-actions.ts ->
use-actions.ts, etc).

Dedupe: drop the duplicate useGitActionHandlers from diff-pane.tsx — the
shared useGitActions hook is the single source. Drop the
buildGitActionsForPane wrapper. Collapse the merge-PR triple fan-out
(mergePrSquash/Merge/RebaseStatus) into one record keyed by
CheckoutPrMergeMethod. Streamline server-side single-use helpers
(dispatchStash/PullRequestMessage adapters, GitHubPullRequestMergeError
wrapper, legacy worktree test helpers).

Schema-additive only: messages.ts exports CheckoutPrMergeMethod and
PullRequestMergeable types; daemon-client.ts uses the typed alias.
Backward-compatible.

Net delta: 43 files, +219/-1212.

* fix(app): use GitHub icon for all merge-PR menu actions

* test: namespace temp GitHub repos under `paseotmp-` and centralize naming

Old prefixes (`paseo-checkout-ship-`, `paseo-e2e-`, `paseo-checkout-pr-merge-`)
collided with the `paseo-*` namespace of real repos, making bulk cleanup
unsafe. Switch every test that creates real GitHub repos to a single
unmistakable `paseotmp-` prefix, owned by one shared helper per test
boundary so no caller can name a repo outside the namespace.

- New `packages/server/src/server/test-utils/temp-github-repo.ts` exports
  `TEMP_GITHUB_REPO_PREFIX` + `createTempGithubRepoName(category)`; both
  server e2e tests (checkout-ship, checkout-pr-merge) consume it.
- `packages/app/e2e/helpers/github-fixtures.ts` locks the prefix internally
  and now requires callers to pass a `category` instead of an arbitrary
  `prefix`. Updated pr-pane and composer-attachments specs accordingly.

packages/app/e2e/composer-attachments.spec.ts

@@ -82,7 +82,7 @@ test.describe("Composer attachments", () => {
     }
 
     const ghRepo = await createTempGithubRepo({
-      prefix: "paseo-e2e-attach-issue-",
+      category: "attach-issue",
       issues: [{ title: "fix: attach-issue-unique-alpha" }],
       prs: [{ title: "feat: attach-issue-dummy-pr", state: "open" }],
     });
@@ -114,7 +114,7 @@ test.describe("Composer attachments", () => {
     }
 
     const ghRepo = await createTempGithubRepo({
-      prefix: "paseo-e2e-attach-pr-",
+      category: "attach-pr",
       prs: [{ title: "feat: attach-pr-unique-beta", state: "open" }],
     });
     const handle = await openGithubWorkspace(page, ghRepo.prs[0].localPath);

packages/app/e2e/helpers/github-fixtures.ts

@@ -153,14 +153,19 @@ function seedIssue(args: { spec: IssueSpec; basePath: string }): GhIssueFixture
   return { number: issueNumber, title: spec.title, url: issueUrl };
 }
 
+// Single namespace for temporary GitHub repos created by Paseo tests.
+// Bulk cleanup relies on this prefix being unmistakable — never reuse `paseo-`
+// (collides with real repos like `paseo`, `paseo-website`).
+const TEMP_GITHUB_REPO_PREFIX = "paseotmp-";
+
 export async function createTempGithubRepo(options: {
-  prefix?: string;
+  category: string;
   prs?: PrSpec[];
   issues?: IssueSpec[];
 }): Promise<GhRepoFixture> {
-  const { prefix = "paseo-e2e-", prs = [], issues = [] } = options;
+  const { category, prs = [], issues = [] } = options;
   const uniqueSuffix = `${Date.now()}-${Math.random().toString(36).slice(2, 7)}`;
-  const repoName = `${prefix}${uniqueSuffix}`;
+  const repoName = `${TEMP_GITHUB_REPO_PREFIX}${category}-${uniqueSuffix}`;
 
   // Bootstrap local git repo
   const basePath = await mkdtemp(path.join("/tmp", `${repoName}-base-`));

packages/app/e2e/helpers/pr-pane.ts

@@ -1,5 +1,5 @@
 import { expect, type Page } from "@playwright/test";
-import { getStateLabel } from "@/utils/pr-pane-data";
+import { getStateLabel } from "@/git/pr-pane-data";
 
 export async function openPrPane(page: Page): Promise<void> {
   await page.getByRole("button", { name: "Open explorer" }).click();

packages/app/e2e/pr-pane.spec.ts

@@ -28,7 +28,7 @@ test.describe("PR pane", () => {
     seedClient = await connectWorkspaceSetupClient();
 
     repoFixture = await createTempGithubRepo({
-      prefix: "paseo-e2e-pr-",
+      category: "pr-pane",
       prs: [
         { title: "Review selected start ref", state: "open" },
         { title: "Merged feature branch", state: "merged" },