fix(firmware): add HTTP timeouts + 3-try retry, report heartbeat status

Unbounded TLS/HTTP POSTs were blocking the reporter task indefinitely
on weak WiFi. Now: 5s connect timeout, 10s response timeout, 3 attempts
with 0/2s/5s backoff. Every attempt logs HTTP_OK or HTTP_FAIL to the
event log. reporter_heartbeat now returns bool so the caller can count
consecutive misses.

firmware/src/reporter.cpp

@@ -1,6 +1,7 @@
 // firmware/src/reporter.cpp
 #include "reporter.h"
 #include "hmac.h"
+#include "event_log.h"
 #include <HTTPClient.h>
 #include <ArduinoJson.h>
 #include <WiFi.h>
@@ -21,25 +22,46 @@ static uint32_t now_ts() {
     return (uint32_t)time(nullptr);
 }
 
-static bool post_json(const DeviceConfig& cfg, const char* path, const String& body) {
+static bool post_json_once(const DeviceConfig& cfg, const char* path, const String& body) {
     uint32_t ts  = now_ts();
-    // Reject if NTP hasn't synced yet (timestamp would be near epoch 0)
+    if (ts < 1700000000UL) return false;
-    if (ts < 1700000000UL) return false; // pre-2023 → clock not valid
     String   sig = hmac_sign(cfg.hmac_secret, "POST", path, ts, body);
-    if (sig.isEmpty()) return false; // HMAC failed
+    if (sig.isEmpty()) return false;
 
     HTTPClient http;
     String url = String(REPORTER_API_HOST) + path;
     http.begin(url);
+    http.setConnectTimeout(5000);   // DNS + TCP connect
+    http.setTimeout(10000);         // per-transaction response timeout
     http.addHeader("Content-Type", "application/json");
     http.addHeader("X-Device-Id",  cfg.device_id);
     http.addHeader("X-Timestamp",  String(ts));
     http.addHeader("X-Signature",  sig);
 
+    uint32_t t0 = millis();
     int code = http.POST(body);
+    uint32_t elapsed = millis() - t0;
     http.end();
-    Serial.printf("[HTTP] POST %s → %d\n", url.c_str(), code);
+    uint16_t phash = event_log_path_hash(path);
-    return (code == 200);
+    Serial.printf("[HTTP] POST %s -> %d (%u ms)\n", url.c_str(), code, (unsigned)elapsed);
+    if (code == 200) {
+        event_log_write(EVT_HTTP_OK, phash, (uint16_t)((elapsed > 65535) ? 65535 : elapsed));
+        return true;
+    }
+    event_log_write(EVT_HTTP_FAIL, phash, (uint16_t)code);
+    return false;
+}
+
+static bool post_json(const DeviceConfig& cfg, const char* path, const String& body) {
+    // 3 attempts with 0/2s/5s delays. Total worst case ~ 2x(5+10)s + 7s = 37s;
+    // acceptable for an hourly task and within the 30s TWDT once Task 6 lands
+    // IF TWDT is fed between attempts (see Task 6).
+    static const uint16_t DELAYS_MS[] = { 0, 2000, 5000 };
+    for (int i = 0; i < 3; i++) {
+        if (DELAYS_MS[i]) vTaskDelay(pdMS_TO_TICKS(DELAYS_MS[i]));
+        if (post_json_once(cfg, path, body)) return true;
+    }
+    return false;
 }
 
 static String build_camera_batch(const DeviceConfig& cfg,
@@ -147,7 +169,7 @@ void reporter_submit_ble(const DeviceConfig& cfg, const BLEHourlyRecord& rec) {
     }
 }
 
-void reporter_heartbeat(const DeviceConfig& cfg, uint32_t uptime_s, int wifi_rssi) {
+bool reporter_heartbeat(const DeviceConfig& cfg, uint32_t uptime_s, int wifi_rssi) {
     JsonDocument doc;
     doc["device_id"]         = cfg.device_id;
     doc["firmware_version"]  = "1.0.0";
@@ -156,7 +178,7 @@ void reporter_heartbeat(const DeviceConfig& cfg, uint32_t uptime_s, int wifi_rss
     doc["pending_records"]   = (int)(s_cam_buf.size() + s_ble_buf.size());
     doc["uptime_seconds"]    = uptime_s;
     String body; serializeJson(doc, body);
-    post_json(cfg, "/api/v1/heartbeat", body);
+    return post_json(cfg, "/api/v1/heartbeat", body);
 }
 
 void reporter_flush(const DeviceConfig& cfg) {

firmware/src/reporter.h

@@ -17,5 +17,5 @@ static const char*  REPORTER_API_HOST   = "http://logs.research.bike";
 void reporter_init();
 void reporter_submit_camera(const DeviceConfig& cfg, const CameraHourlyRecord& rec);
 void reporter_submit_ble(const DeviceConfig& cfg, const BLEHourlyRecord& rec);
-void reporter_heartbeat(const DeviceConfig& cfg, uint32_t uptime_s, int wifi_rssi);
+bool reporter_heartbeat(const DeviceConfig& cfg, uint32_t uptime_s, int wifi_rssi);
 void reporter_flush(const DeviceConfig& cfg);