chore: scaffold payroll extension

Repo tooling and LNbits extension metadata only — no runtime code yet, so
this lands separately from the feature work per the workspace commit rules
(cross-cutting concerns commit first).

- MIT licence, .gitignore, README
- Makefile + pyproject wired for the standard aio fork lint pipeline
  (black + ruff + mypy) and pytest
- config.json declaring id/version/tile so the extension is installable
  from the aiolabs catalog once there is something to install

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018jy52j9GRZ6XKa1Zt21LLj

config.json

@@ -0,0 +1,23 @@
+{
+  "id": "payroll",
+  "version": "0.1.0",
+  "name": "Payroll",
+  "repo": "https://git.atitlan.io/aiolabs/payroll",
+  "short_description": "Scheduled recurring salary payouts between LNbits wallets",
+  "description": "",
+  "tile": "/payroll/static/image/payroll.png",
+  "min_lnbits_version": "1.4.1",
+  "contributors": [
+    {
+      "name": "padreug",
+      "uri": "https://git.atitlan.io/padreug",
+      "role": "Author"
+    }
+  ],
+  "images": [],
+  "license": "MIT",
+  "paid_features": "",
+  "tags": ["Finance"],
+  "donate": "",
+  "hidden": false
+}