Implement story 1.1: project scaffold and verified entry points

Creates the complete src/planemapper/ layout with all module stubs,
provisioning and renderer subpackages, airports.csv data bundle,
systemd unit files, and full test scaffold. All three quality gates
pass: pytest 12/12, ruff check zero violations, ruff format clean.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/planemapper/gpio_ctrl.py

@@ -0,0 +1,11 @@
+class ButtonHoldDetector:
+    def check(self) -> bool:
+        return False
+
+
+class LEDController:
+    def on(self) -> None:
+        pass
+
+    def off(self) -> None:
+        pass