M7: touch + outbound /state POST to Scrypted

state_client.{h,c}:
- Worker task drains a depth-1 queue (xQueueOverwrite gives the
  replace-on-full semantics from the spec — in-flight POST is never
  cancelled; the next queued entry is overwritten by newer state).
- esp_http_client POST to <scrypted>/state with Content-Type application/
  json, User-Agent ScryptedViewport/<version>, Connection: close, 1s
  timeout. Body: {"viewport":"<name>","state":"wake"|"sleep"}.
- Any non-2xx or transport error increments state_post_failures and is
  otherwise ignored. Silently drops if no Scrypted URL is configured.

touch.{h,c}:
- FT5426 capacitive touch on the shared I2C bus at 0x38.
- 30ms polling task; tracks down/up transitions, detects taps as
  down-then-up within 500ms with a 150ms debounce.
- On tap, toggles wake/sleep via state_machine_set_local(), which drives
  the local transition AND fires state_client_post() at Scrypted.

state_machine adds state_machine_set_local(): runs the same transition
as state_machine_set() then enqueues an outbound POST. Idle-timer
expiry now uses this path so Scrypted sees idle-driven sleeps too
(the spec's "tighten the race with /frame 409" path stays in place as
the fallback).

display.h exposes display_i2c_bus(); touch.c uses it instead of
re-initializing the same I2C port.

app_main starts state_client right after the state machine and starts
touch after display init (touch is skipped if display isn't up since
they share the bus).

CMakeLists.txt: add esp_http_client to REQUIRES.

Build clean against ESP-IDF 5.4 (binary ~860 KB; jumped ~210 KB from
M6 because esp_http_client + cJSON path pulls in tcp_transport, mbedtls,
http_parser).

TESTING.md M7: flask-based test receiver, tap dispatch verification,
failure-path check (kill receiver, confirm counter increments),
queue-coalescing behavior, no-POST-on-Scrypted-initiated, no-POST-
when-unconfigured.

1 files changed, 18 insertions, 0 deletions

diff --git a/main/state_client.h b/main/state_client.h
new file mode 100644
index 0000000..bf7e1c6
--- /dev/null
+++ b/main/state_client.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "esp_err.h"
+#include "viewport_state.h"
+
+esp_err_t state_client_init(void);
+
+// Queue a state-change POST to <scrypted>/state.
+//
+// Concurrency model (per spec):
+//   - At most one HTTP POST in flight; a dedicated worker task drives it.
+//   - Depth-1 queue. If a POST is already queued, replace it with the newer
+//     one — the in-flight POST is never cancelled.
+//   - Fire-and-forget from the caller's perspective. Local state change
+//     proceeds immediately regardless of POST outcome.
+//
+// Silently dropped if the device has no Scrypted URL configured.
+void state_client_post(viewport_run_state_t state);