Add M0 services: settings, battery, clock, storage, power

lib/services holds the host-tested logic:
- Settings: typed, validated, persisted, SettingChanged events,
  transmit gated on a confirmed Region
- BatteryEstimator: LiPo curve, median smoothing against TX sags
- ClockModel: source priority GNSS > NTP > mesh, relative ages,
  Europe/Brussels local time via POSIX TZ
- StorageMonitor: warning once per boot at 80%, Logs stop at 90%,
  Captures stop with < 2 MiB left
- PowerPolicy / PowerButton: dim/off timeouts, wake key swallowed only
  when the screen was off, G0 long press

src/services wires them to the hardware (NVS, battery ADC, SD on the
shared SPI bus with the LoRa CS held high, backlight, deep sleep), and
main.cpp is a temporary diagnostics screen for the hardware checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/platform/pins.h

@@ -0,0 +1,17 @@
+#pragma once
+
+// Cardputer ADV + Cap LoRa-1262 pin map (see docs.m5stack.com).
+namespace roro::pins {
+
+constexpr int kBatteryAdc = 10;  // through a 1:2 divider
+
+constexpr int kButtonG0 = 0;
+
+// SPI bus shared by the microSD card and the LoRa radio.
+constexpr int kSpiSck = 40;
+constexpr int kSpiMiso = 39;
+constexpr int kSpiMosi = 14;
+constexpr int kSdCs = 12;
+constexpr int kLoraCs = 5;
+
+}  // namespace roro::pins