Snapshot iniziale: bridge telemetria CRSF->LTM/MAVLink (ESP-NOW)

Stato di partenza prima dei fix. Il repo git era inizializzato a meta'
(config.lock + objects/ mancante, zero commit): riparato.
my_config.h (UID reale, tutti e 3 i sottoprogetti) escluso via .gitignore;
aggiunto my_config.h.example. .pio/ escluso.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

02_telemetry_bridge/lib/Ltm/Ltm.cpp

@@ -0,0 +1,57 @@
+#include "Ltm.h"
+
+namespace Ltm {
+
+// Scrive header "$T<code>" in out, ritorna l'indice del primo byte payload (3).
+static inline size_t header(uint8_t* out, char code) {
+    out[0] = '$';
+    out[1] = 'T';
+    out[2] = (uint8_t)code;
+    return 3;
+}
+
+// Calcola CRC (XOR del payload da [3] a [n-1]) e lo appende. Ritorna n+1.
+static inline size_t finalise(uint8_t* out, size_t n) {
+    uint8_t crc = 0;
+    for (size_t i = 3; i < n; ++i) crc ^= out[i];
+    out[n] = crc;
+    return n + 1;
+}
+
+static inline void wU16(uint8_t* p, uint16_t v) { p[0] = v & 0xFF; p[1] = (v >> 8) & 0xFF; }
+static inline void wU32(uint8_t* p, uint32_t v) {
+    p[0] = v & 0xFF; p[1] = (v >> 8) & 0xFF; p[2] = (v >> 16) & 0xFF; p[3] = (v >> 24) & 0xFF;
+}
+
+size_t gframe(uint8_t* out, int32_t lat, int32_t lon,
+              uint8_t gs_mps, int32_t alt_cm, uint8_t sats, uint8_t fix) {
+    size_t n = header(out, 'G');
+    wU32(&out[n], (uint32_t)lat);     n += 4;
+    wU32(&out[n], (uint32_t)lon);     n += 4;
+    out[n++] = gs_mps;
+    wU32(&out[n], (uint32_t)alt_cm);  n += 4;
+    out[n++] = (uint8_t)((sats << 2) | (fix & 0x03));
+    return finalise(out, n);          // 18 byte
+}
+
+size_t aframe(uint8_t* out, int16_t pitch, int16_t roll, int16_t heading) {
+    size_t n = header(out, 'A');
+    wU16(&out[n], (uint16_t)pitch);   n += 2;
+    wU16(&out[n], (uint16_t)roll);    n += 2;
+    wU16(&out[n], (uint16_t)heading); n += 2;
+    return finalise(out, n);          // 10 byte
+}
+
+size_t sframe(uint8_t* out, uint16_t vbat_mv, uint16_t current,
+              uint8_t rssi, uint8_t airspeed,
+              uint8_t flightmode, uint8_t statemode) {
+    size_t n = header(out, 'S');
+    wU16(&out[n], vbat_mv);  n += 2;
+    wU16(&out[n], current);  n += 2;
+    out[n++] = rssi;
+    out[n++] = airspeed;
+    out[n++] = (uint8_t)((flightmode << 2) | (statemode & 0x03));
+    return finalise(out, n);          // 11 byte
+}
+
+} // namespace Ltm