chore: add commit-msg hook to strip Cursor co-author trailers

Document enabling .githooks so IDE-added Co-authored-by lines are not committed.

Author: redanthrax

.githooks/commit-msg

@@ -0,0 +1,7 @@
+#!/bin/sh
+# Strip Cursor co-author trailers added by IDE tooling.
+if [ -f "$1" ]; then
+	sed -i.bak '/^Co-authored-by: Cursor /d' "$1"
+	rm -f "$1.bak"
+fi
+exit 0

README.md

@@ -15,6 +15,12 @@ pnpm run build
 
 Use **pnpm only** for installs in this repo. With Corepack enabled, `npm install` and `yarn install` are rejected. Do not commit `package-lock.json` or `yarn.lock` (see [SECURITY.md](SECURITY.md)).
 
+**Git hooks (recommended):** enable `.githooks/commit-msg` once per clone so Cursor co-author trailers are stripped from commit messages:
+
+```bash
+git config core.hooksPath .githooks
+```
+
 ### Testing locally
 
 **Unit tests** (no HaloPSA credentials required):