Add status_led package: network, API, error and OTA status on a visible RGB light

Red blink without network, orange without an API client, purple on a
component error, blue blink during OTA, green when things are back to
normal, then the light returns to its previous state.

echo uses it on the gateway LED ring; drop its status_led on GPIO23,
which never worked because the ledc output owns that pin.

common/status_led.yaml

@@ -0,0 +1,126 @@
+---
+# Status on a visible RGB light, which stays a normal light otherwise:
+#   network down         red, slow blink
+#   no API client (HA)   orange, slow blink
+#   component error      purple, steady
+#   OTA                  blue, fast blink; green when done, 3 red blinks on error
+#   back to normal       green for 1 s, then the light goes back to how it was
+#   packages:
+#     status_led: !include
+#       file: common/status_led.yaml
+#       vars:
+#         light_id: led_light
+# Needs the ota id ota_esphome (common/ota_esp32.yaml).
+defaults:
+  brightness: "0.3"
+
+globals:
+  - id: status_led_active
+    type: bool
+    initial_value: "false"
+  - id: status_led_saved
+    type: light::LightColorValues
+  - id: status_led_last
+    type: uint32_t
+    initial_value: "0xFFFFFFFF"
+
+script:
+  - id: status_led_show
+    parameters:
+      r: float
+      g: float
+      b: float
+      lit: bool
+    then:
+      - lambda: |-
+          auto *l = id(${light_id});
+          uint32_t key = (lit << 24) | (uint32_t(r * 255) << 16) | (uint32_t(g * 255) << 8) | uint32_t(b * 255);
+          if (!id(status_led_active)) {
+            id(status_led_saved) = l->remote_values;
+            id(status_led_active) = true;
+          } else if (key == id(status_led_last)) {
+            return;  // unchanged: don't flood Home Assistant with the same state
+          }
+          id(status_led_last) = key;
+          if (lit) {
+            l->turn_on().set_rgb(r, g, b).set_brightness(${brightness}).set_transition_length(0).set_effect("None").perform();
+          } else {
+            l->turn_off().set_transition_length(0).perform();
+          }
+          l->loop();  // write now: OTA blocks the main loop
+  - id: status_led_restore
+    parameters:
+      confirm: bool
+    then:
+      - lambda: |-
+          if (id(status_led_active) && confirm) id(status_led_show)->execute(0.0f, 1.0f, 0.0f, true);
+      - if:
+          condition:
+            lambda: 'return id(status_led_active) && confirm;'
+          then:
+            - delay: 1s  # green: back to normal
+      - lambda: |-
+          if (!id(status_led_active)) return;
+          id(status_led_active) = false;
+          id(status_led_last) = 0xFFFFFFFF;
+          id(${light_id})->make_call().from_light_color_values(id(status_led_saved)).set_transition_length(0).perform();
+
+interval:
+  - interval: 500ms
+    then:
+      - lambda: |-
+          static uint8_t tick = 0;
+          tick++;
+          bool slow = (tick / 2) % 2 == 0;  // 1 s on, 1 s off
+          bool problem = !network::is_connected() || !api::global_api_server->is_connected() ||
+                         (App.get_app_state() & STATUS_LED_ERROR);
+          if (problem) id(status_led_restore)->stop();
+          if (!network::is_connected()) {
+            id(status_led_show)->execute(1.0f, 0.0f, 0.0f, slow);
+          } else if (!api::global_api_server->is_connected()) {
+            id(status_led_show)->execute(1.0f, 0.4f, 0.0f, slow);
+          } else if (App.get_app_state() & STATUS_LED_ERROR) {
+            id(status_led_show)->execute(0.6f, 0.0f, 1.0f, true);
+          } else if (id(status_led_active) && !id(status_led_restore)->is_running()) {
+            id(status_led_restore)->execute(true);
+          }
+
+ota:
+  - id: !extend ota_esphome
+    on_begin:
+      - script.execute:
+          id: status_led_show
+          r: 0.0
+          g: 0.0
+          b: 1.0
+          lit: true
+    on_progress:
+      - lambda: 'id(status_led_show)->execute(0.0f, 0.0f, 1.0f, (millis() / 250) % 2 == 0);'
+    on_end:
+      - script.execute:
+          id: status_led_show
+          r: 0.0
+          g: 1.0
+          b: 0.0
+          lit: true
+    on_error:
+      - repeat:
+          count: 3
+          then:
+            - script.execute:
+                id: status_led_show
+                r: 1.0
+                g: 0.0
+                b: 0.0
+                lit: true
+            - delay: 250ms
+            - script.execute:
+                id: status_led_show
+                r: 1.0
+                g: 0.0
+                b: 0.0
+                lit: false
+            - delay: 250ms
+      - script.execute:
+          id: status_led_restore
+          confirm: false