M2: HTTP server + mDNS service discovery + shared state

- viewport_state.{h,c}: shared state struct (config, run-state, counters,
  orientation, timestamps) behind a FreeRTOS mutex. Modules update it
  under viewport_state_lock(); GET /state serializes a snapshot.
- http_api.{h,c}: starts esp_http_server on :80, registers GET /state.
  Returns the full JSON shape from the spec (name, version, configured,
  state, uptime_ms, last_frame_ms_ago, frames_received, decode_errors,
  state_post_failures, resolution, ip, free_heap, free_psram).
- mdns_service.{h,c}: mdns_init + advertise _scrypted-viewport._tcp.local
  on :80 with version/resolution/orientation/name TXT records.
  mdns_service_refresh() reapplies hostname + TXT after /config writes
  (called from M4 onward).
- main/CMakeLists.txt: add esp_http_server, esp_timer, json, mdns to
  REQUIRES. espressif/mdns added as managed component via
  main/idf_component.yml.

app_main calls viewport_state_init early so any module can read defaults
before /config arrives.

Also adds TESTING.md tracking per-milestone verification status and an
integration test plan to run after M9 (races, failure modes, longevity,
power cycles, negative protocol, multi-viewport).

M1 promoted to "🟡 builds clean" in TESTING.md; combined HW verification
of M1+M2 will be one flash session. Build verified against ESP-IDF 5.4
for target esp32p4 (binary ~550 KB).

1 files changed, 10 insertions, 5 deletions

diff --git a/main/app_main.c b/main/app_main.c
index 8b91537..9389642 100644
--- a/main/app_main.c
+++ b/main/app_main.c
@@ -1,4 +1,7 @@
+#include "http_api.h"
+#include "mdns_service.h"
 #include "net_eth.h"
+#include "viewport_state.h"
 
 #include "esp_event.h"
 #include "esp_log.h"
@@ -13,7 +16,8 @@ void app_main(void)
     ESP_ERROR_CHECK(esp_netif_init());
     ESP_ERROR_CHECK(esp_event_loop_create_default());
 
-    ESP_LOGI(TAG, "Scrypted Viewport boot");
+    viewport_state_init();
+    ESP_LOGI(TAG, "Scrypted Viewport boot (v%s)", VIEWPORT_VERSION);
 
     ESP_ERROR_CHECK(net_eth_init());
     if (net_eth_wait_for_ip(30 * 1000) == ESP_OK) {
@@ -22,12 +26,13 @@ void app_main(void)
         ESP_LOGW(TAG, "no DHCP lease after 30s, will keep retrying in the background");
     }
 
-    // TODO M2: mDNS _scrypted-viewport._tcp.local
-    // TODO M2: HTTP server: GET /state
+    ESP_ERROR_CHECK(mdns_service_start());
+    ESP_ERROR_CHECK(http_api_start());
+
     // TODO M3: MIPI-DSI panel init (800x480 IPS, default portrait 480x800)
-    // TODO M4: /config persistence (NVS)
+    // TODO M4: /config persistence (NVS) + GET /config + POST /config
     // TODO M5: /frame JPEG decode -> framebuffer
-    // TODO M6: /state POST + idle timer
+    // TODO M6: POST /state + idle timer
     // TODO M7: Capacitive touch -> outbound /state POST
     // TODO M8: Local screens (IP, loading) + BOOT button
 }