thinknode_m9: pick GPS enable polarity from the board revision

The GPS enable pin (GPIO11) is active-LOW on the original ThinkNode-M9 but
active-HIGH on the newer revision (keyboard controller at 0x6D, e.g. Elecrow's
Meshtastic SKU LMM15409D2). Driven LOW on those units the GPS never gets a
fix: on one unit, same spot, 0 satellites with EN active-LOW vs 15 with
active-HIGH, and 34 after 20 minutes outdoors with the GPS toggled off and on
again from the UI. Meshtastic's ELECROW-ThinkNode-M9 variant makes the same
split, keyed on the same keyboard address (m9Version > 1 ? HIGH : LOW), and
Elecrow engineers have confirmed the split.

WadaNmeaLocationProvider: keep the enable level in a member that defaults to
the compile-time GPS_EN_ACTIVE, add setEnActive() to override it at runtime
(re-driving the pin so a running GPS stays on), and an optional
setPostEnableHook() run at the end of begin(). Every other board is unaffected.

thinknode_m9: m9KeyboardAddr() and a one-shot found-callback on the keyboard
driver; target.cpp uses it, when the controller is at 0x6D, to call
gps.setEnActive(true) and to register a GPIO10 wake pulse (50 ms, HIGH 5 ms,
LOW, 50 ms) after enabling, as Elecrow engineers confirmed. Any other address
keeps the existing default (LOW, no pulse), so the 0x6C path is unchanged; it
is not tested here, no 0x6C unit was available.

Depends on the keyboard 0x6D probe change.

Signed-off-by: Pratik Patel <Pratik@MakerNova.io>

variants/thinknode_m9/M9Keyboard.cpp

@@ -27,6 +27,8 @@ static volatile uint8_t s_ring[16];
 static volatile uint8_t s_head = 0;
 static volatile uint8_t s_tail = 0;
 static bool             s_inited = false;
+static void           (*s_found_cb)(uint8_t) = nullptr;
+static bool             s_found_cb_done = false;
 static TwoWire*         s_bus = nullptr;      // set once the controller answers
 static uint8_t          s_address = PIN_KB_ADDR;
 static uint32_t         s_last_probe_ms = 0;
@@ -59,10 +61,15 @@ static void kbTryFindBus() {
   const uint8_t addresses[] = {PIN_KB_ADDR, M9_KB_V11_ADDR};
   for (uint8_t address : addresses) {
     if (kbProbe(Wire1, "Wire1 (20/21)", address) ||
-        kbProbe(Wire, "Wire (7/6)", address)) return;
+        kbProbe(Wire, "Wire (7/6)", address)) break;
   }
+  if (s_bus && s_found_cb && !s_found_cb_done) { s_found_cb_done = true; s_found_cb(s_address); }
 }
 
+uint8_t m9KeyboardAddr() { return s_bus ? s_address : 0; }
+
+void m9KeyboardSetFoundCallback(void (*cb)(uint8_t addr)) { s_found_cb = cb; s_found_cb_done = false; }
+
 void m9KeyboardBegin() {
   Wire1.begin(PIN_KB_SDA, PIN_KB_SCL);
   // The controller is its own MCU (ESP32-S2) on the ALWAYS-ON 3V3 rail via R3