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

lib/services/src/settings.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <array>
+#include <string>
+
+#include "event_bus.h"
+#include "key_value_store.h"
+
+namespace roro {
+
+enum class Setting : uint8_t {
+    SetupDone,        // bool: first-boot wizard completed
+    LongName,         // string, 1..39 bytes
+    ShortName,        // string, 1..4 bytes
+    Region,           // string, a known Region ("EU868")
+    RegionConfirmed,  // bool: nothing transmits until true
+    Timezone,         // string, POSIX TZ
+    Brightness,       // int, 10..100 %
+    DimTimeoutS,      // int, 5..600, below OffTimeoutS
+    OffTimeoutS,      // int, 10..3600, above DimTimeoutS
+    Sound,            // bool
+    ProbeMacRaw,      // bool: probe-request Logs keep raw MAC addresses
+    Count
+};
+
+// Typed, validated settings in internal flash. Every accepted change is persisted immediately and
+// announced with a SettingChanged event; rejected values leave the current value untouched.
+class Settings {
+   public:
+    Settings(KeyValueStore& store, EventBus& bus);
+
+    // Reads every setting; missing or invalid stored values fall back to defaults.
+    void load();
+
+    int32_t getInt(Setting s) const;
+    bool getBool(Setting s) const;
+    const std::string& getString(Setting s) const;
+
+    bool setInt(Setting s, int32_t value);
+    bool setBool(Setting s, bool value);
+    bool setString(Setting s, const std::string& value);
+
+    bool canTransmit() const { return getBool(Setting::RegionConfirmed); }
+
+    static const char* key(Setting s);
+
+   private:
+    struct Value {
+        int32_t i = 0;
+        std::string str;
+    };
+
+    bool validInt(Setting s, int32_t value) const;
+    bool validString(Setting s, const std::string& value) const;
+    void changed(Setting s);
+
+    KeyValueStore& store_;
+    EventBus& bus_;
+    std::array<Value, static_cast<size_t>(Setting::Count)> values_;
+};
+
+}  // namespace roro