Add firmware function events

docs/firmware_proto_transport.md

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+# Firmware Proto Transport
+
+## Goal
+
+Add CDC and GATT private communication without rewriting the existing keyboard,
+time, theme, and LED business logic.
+
+The firmware side should:
+
+- keep standard HID behavior for normal keys
+- receive host commands over CDC and GATT
+- report private state and function key events over CDC and GATT
+- reuse existing modules where possible
+
+## Completed Nodes
+
+### Node 1: internal function events
+
+Files:
+
+- `src/events/function_bitmap_event.h`
+- `src/events/function_bitmap_event.c`
+- `src/events/function_key_event.h`
+- `src/events/function_key_event.c`
+
+Design notes:
+
+- `function_bitmap_event` carries the 29-byte function bitmap from host
+- `function_key_event` carries usage + action when a configured function key
+  is pressed or released
+- these events isolate transport modules from keyboard internals
+
+## Planned next nodes
+
+- keyboard split logic uses `function_bitmap_event`
+- CDC transport module
+- GATT transport module
+- nanopb integration and generated protocol code

src/events/function_bitmap_event.c

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+#include "function_bitmap_event.h"
+
+static void log_function_bitmap_event(const struct app_event_header *aeh)
+{
+	const struct function_bitmap_event *event =
+		cast_function_bitmap_event(aeh);
+
+	APP_EVENT_MANAGER_LOG(aeh, "len=%u", event->dyndata.size);
+}
+
+static void profile_function_bitmap_event(struct log_event_buf *buf,
+					  const struct app_event_header *aeh)
+{
+	const struct function_bitmap_event *event =
+		cast_function_bitmap_event(aeh);
+
+	nrf_profiler_log_encode_uint16(buf, event->dyndata.size);
+}
+
+APP_EVENT_INFO_DEFINE(function_bitmap_event,
+		      ENCODE(NRF_PROFILER_ARG_U16),
+		      ENCODE("len"),
+		      profile_function_bitmap_event);
+
+APP_EVENT_TYPE_DEFINE(function_bitmap_event,
+		      log_function_bitmap_event,
+		      &function_bitmap_event_info,
+		      APP_EVENT_FLAGS_CREATE(APP_EVENT_TYPE_FLAGS_INIT_LOG_ENABLE));

src/events/function_bitmap_event.h

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+#ifndef FUNCTION_BITMAP_EVENT_H__
+#define FUNCTION_BITMAP_EVENT_H__
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <app_event_manager.h>
+#include <app_event_manager_profiler_tracer.h>
+
+struct function_bitmap_event {
+	struct app_event_header header;
+	struct event_dyndata dyndata;
+};
+
+APP_EVENT_TYPE_DYNDATA_DECLARE(function_bitmap_event);
+
+static inline void function_bitmap_event_submit(const uint8_t *data, size_t size)
+{
+	struct function_bitmap_event *event = new_function_bitmap_event(size);
+
+	if ((size > 0U) && (data != NULL)) {
+		memcpy(event->dyndata.data, data, size);
+	}
+
+	APP_EVENT_SUBMIT(event);
+}
+
+static inline const uint8_t *function_bitmap_event_get_data(
+	const struct function_bitmap_event *event)
+{
+	return event->dyndata.data;
+}
+
+static inline size_t function_bitmap_event_get_size(
+	const struct function_bitmap_event *event)
+{
+	return event->dyndata.size;
+}
+
+#endif /* FUNCTION_BITMAP_EVENT_H__ */

src/events/function_key_event.c

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+#include "function_key_event.h"
+
+static void log_function_key_event(const struct app_event_header *aeh)
+{
+	const struct function_key_event *event =
+		cast_function_key_event(aeh);
+
+	APP_EVENT_MANAGER_LOG(aeh, "usage=0x%04x pressed=%u",
+			      event->usage,
+			      event->pressed);
+}
+
+static void profile_function_key_event(struct log_event_buf *buf,
+				       const struct app_event_header *aeh)
+{
+	const struct function_key_event *event =
+		cast_function_key_event(aeh);
+
+	nrf_profiler_log_encode_uint16(buf, event->usage);
+	nrf_profiler_log_encode_uint8(buf, event->pressed ? 1U : 0U);
+}
+
+APP_EVENT_INFO_DEFINE(function_key_event,
+		      ENCODE(NRF_PROFILER_ARG_U16,
+			     NRF_PROFILER_ARG_U8),
+		      ENCODE("usage", "pressed"),
+		      profile_function_key_event);
+
+APP_EVENT_TYPE_DEFINE(function_key_event,
+		      log_function_key_event,
+		      &function_key_event_info,
+		      APP_EVENT_FLAGS_CREATE(APP_EVENT_TYPE_FLAGS_INIT_LOG_ENABLE));

src/events/function_key_event.h

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+#ifndef FUNCTION_KEY_EVENT_H__
+#define FUNCTION_KEY_EVENT_H__
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <app_event_manager.h>
+#include <app_event_manager_profiler_tracer.h>
+
+struct function_key_event {
+	struct app_event_header header;
+	uint16_t usage;
+	bool pressed;
+};
+
+APP_EVENT_TYPE_DECLARE(function_key_event);
+
+static inline void function_key_event_submit(uint16_t usage, bool pressed)
+{
+	struct function_key_event *event = new_function_key_event();
+
+	event->usage = usage;
+	event->pressed = pressed;
+	APP_EVENT_SUBMIT(event);
+}
+
+#endif /* FUNCTION_KEY_EVENT_H__ */