Sign the macOS bundle, or it arrives "damaged"

The first release could not be opened: macOS said "WarpEngine Store is damaged
and can't be opened. You should move it to the Bin."

Not a wording problem — an integrity one. electron-builder found no signing
identity and skipped signing, so the bundle kept only the linker's ad-hoc
signature on its main executable, with no resource seal. `codesign --verify` said
"code has no resources but signature indicates they must be present", and
Gatekeeper reports that as damaged and offers no way past it, unlike an
un-notarised app which can at least be approved.

`scripts/after-pack.js` now signs the bundle itself during packaging. Measured on
a copy unzipped from the artifact with the quarantine flag set by hand:

  before  code has no resources but signature indicates they must be present
  after   valid on disk; satisfies its Designated Requirement

and the identifier is ours rather than `Electron`. `syspolicy_check` is down to
its expected "adhoc signed" warning. A downloaded copy still has to be approved —
that is Gatekeeper policy for anything un-notarised, and notarisation needs a paid
Developer ID — so the README and the release notes lead with the one command that
does it.

Two smaller things the failure turned up:

- The self-test was passing silently. With a copy of the app already open, the
  second process lost the single-instance lock and exited 0 with no output, which
  reads exactly like success. It now uses its own user-data directory and skips
  the lock, and it caught a real launch failure immediately afterwards.
- The README claimed right-click ▸ Open was enough. It was not, and I had not
  checked it — replaced with what the measurements support.

v1.0.0's attachments are withdrawn rather than left downloadable.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -27,10 +27,27 @@ Grab the package for your machine from the
 and open it. On first run, if there is no store on the machine yet, the window
 offers to download one — that is the whole setup.
 
-The macOS build is **not signed or notarised**, so the first open needs
-*right-click ▸ Open* (or *System Settings ▸ Privacy & Security*). Nothing the
-store itself downloads is affected: those files are fetched by Python, which does
-not set the quarantine flag.
+### Opening it on macOS
+
+The build is ad-hoc signed but **not notarised**, so macOS asks before running a
+copy that came from a browser. The reliable way through:
+
+```sh
+xattr -dr com.apple.quarantine "/Applications/WarpEngine Store.app"
+```
+
+If macOS offers *Open Anyway* under **System Settings ▸ Privacy & Security** after
+a blocked attempt, that works as well. Notarisation is the only thing that removes
+the step entirely, and it needs a paid Apple Developer ID.
+
+Nothing the store itself downloads is affected: Python fetches those files, and
+Python does not set the quarantine flag.
+
+**v1.0.0 could not be opened at all** — it reported *"is damaged"*. The bundle had
+never been signed; only its main executable carried the linker's ad-hoc signature,
+so there was no resource seal and Gatekeeper refused it outright rather than
+asking. `scripts/after-pack.js` signs the bundle during the build now, and the
+result verifies as `valid on disk`.
 
 ## Use
 
@@ -61,6 +78,10 @@ npm run dist:mac           # or dist:win / dist:linux
 is ESM-only, and older Node cannot `require()` it. The packaged app carries its
 own runtime.
 
+`npm run uitest` runs with its own user-data directory and without the
+single-instance lock. Otherwise a copy the user already has open swallows the test
+process, which exits 0 and reads as a pass.
+
 Both test scripts accept a sandbox store instead of the real one, which is how
 this repository is tested without touching a working installation:
 
@@ -95,10 +116,17 @@ too — that is why the indirection is there.
 
 ## Verified, and not
 
-Exercised on macOS (arm64): the store is discovered, the catalog lists, a sync
-installs, the window renders the installed state, and `npm run uitest` passes with
-the grid rendered and both languages in the picker. The bootstrap download was run
-into an empty directory and the resulting store answered the bridge.
+Exercised on macOS (arm64), with the packaged app from the release rather than a
+dev run: the store is discovered, the catalog lists, a sync installs, the window
+renders the installed state, and `npm run uitest` passes with the grid rendered
+and both languages in the picker. The bootstrap download was run into an empty
+directory and the resulting store answered the bridge.
+
+The signing was measured rather than assumed, by setting the quarantine flag on a
+copy unzipped from the release artifact: `codesign --verify --deep --strict` is
+clean, and `syspolicy_check` reports only the expected *"adhoc signed"* warning.
+A quarantined copy is still stopped until it is approved — that part is Gatekeeper
+policy, not a fault in the package.
 
 **Not tried on Linux or Windows.** The paths and the launch behaviour are written
 for them, and the store CLI itself has the same gap — `.desktop` and `.lnk`