M3 step 4: the LoRa Scanner App, Sniffer and Captures

The Sniffer lists packets newest first (time, RSSI, SNR, and for
Meshtastic the sender, receiver and hops), with the clear header and a
hex dump on Enter (Q96); `p` picks an EU868 preset, kept in Settings
(Q95). `c` starts a Capture: pcap with LoRaTap in /captures/lora, its own
Clean-up category, recorded by a small Service so it carries on with the
App closed (Q97, Q100). The Status Bar shows L while listening, bright on
each packet, and CAP while capturing (Q101). StorageService gains raw
appends for binary files. Debug Builds get `lora inject` to test all of
this with no transmitter in range: a Capture made on the device reads
back in TShark field for field.

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

lib/lora/src/loratap.cpp

@@ -2,6 +2,8 @@
 
 #include <algorithm>
 #include <cmath>
+#include <cstdio>
+#include <ctime>
 
 namespace roro::lora {
 
@@ -16,6 +18,16 @@ static uint8_t dbmByte(float dbm) {
     return static_cast<uint8_t>(std::clamp(v, 0L, 255L));
 }
 
+std::string capturePath(int64_t utcSeconds) {
+    time_t t = static_cast<time_t>(utcSeconds);
+    struct tm u;
+    gmtime_r(&t, &u);
+    char buf[48];
+    std::snprintf(buf, sizeof buf, "/captures/lora/%04d%02d%02d-%02d%02d%02d.pcap", u.tm_year + 1900, u.tm_mon + 1,
+                  u.tm_mday, u.tm_hour, u.tm_min, u.tm_sec);
+    return buf;
+}
+
 void appendPcapHeader(std::vector<uint8_t>& out) {
     le32(out, 0xA1B2C3D4);
     le16(out, 2);