app-module events & callstack config, crash diagnostics (#630)

- Apps can specify task stack depth and preferred memory placement in their manifests.
- App identifiers are validated against length and character requirements.
- Crash diagnostics now show the crash cause, reason, fault address, call stack, and program-counter details, with logs saved for review.
- App closing is more consistent across built-in screens. There's now a dedicated function, and the old _emit() function is made private.
- Crash diagnostics no longer display a QR code without a call stack.
- Improved memory allocation for unrestricted requests.

Modules/app-module/include/app/event.h

@@ -114,16 +114,6 @@ error_t app_event_subscribe_with_app_id(struct AppEventSubscription* sub, struct
  */
 error_t app_event_unsubscribe(struct AppEventSubscription* sub);
 
-/**
- * Deliver @a event to every subscription registered for @a app_instance_id (normally exactly one).
- * @warning Does not work in ISR context.
- * @retval ERROR_NONE delivered to at least one subscription
- * @retval ERROR_NOT_FOUND no subscription is registered for @a app_instance_id
- * @retval ERROR_RESOURCE at least one matching subscription's queue was full; the event was
- * dropped for that subscription (still delivered to any other matching subscription)
- */
-error_t app_event_emit(AppInstanceId app_instance_id, const struct AppEvent* event);
-
 /**
  * Non-blocking: pop the next event for @a sub if one is already queued.
  * @warning Never blocks. To wait for an event, block in task_event_group_wait()/
@@ -134,6 +124,13 @@ error_t app_event_emit(AppInstanceId app_instance_id, const struct AppEvent* eve
  */
 error_t app_event_poll(struct AppEventSubscription* sub, struct AppEvent* out_event);
 
+/**
+ * Emits a close event to the specified app.
+ * @param[in] instance_id
+ * @return ERROR_NONE when event was successfully emitted
+ */
+error_t app_event_emit_close(AppInstanceId instance_id);
+
 #ifdef __cplusplus
 }
 #endif

Modules/app-module/include/app/manifest.h

@@ -3,12 +3,16 @@
 
 #include "location.h"
 
+#include <stddef.h>
 #include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+// Character count, excluding null terminator
+#define APP_ID_LENGTH 32
+
 /** Broad classification of an app, used for grouping/launcher presentation. */
 enum AppCategory {
     APP_CATEGORY_SYSTEM,
@@ -24,6 +28,21 @@ enum AppManifestFlags {
     APP_MANIFEST_FLAG_HIDDEN = 1 >> 0,
 };
 
+/** Largest stack depth (in words) an app may request. Keeps `depth * sizeof(StackType_t)` safely
+ * bounded and stops one app from claiming an unreasonable share of available RAM. A depth beyond
+ * this must be rejected outright, not silently truncated or clamped. */
+#define APP_STACK_SIZE_MAX 16384
+
+struct AppStackConfig {
+    /** Stack depth (in words, matching FreeRTOS's configSTACK_DEPTH_TYPE) for this app's task.
+     * 0 uses the scheduler's default. Must not exceed APP_STACK_SIZE_MAX. */
+    uint16_t depth;
+    /** Desired memory capability.
+     * 0 means default.
+     * Combine one or more of \a MemoryCapability from <tactility/memory.h> with a bitwise OR.*/
+    uint16_t desired_memory_capability;
+};
+
 /** Describes a registrable app. One manifest exists per app id. */
 struct AppManifest {
     /** Unique app identifier. Should never be NULL. */
@@ -34,8 +53,12 @@ struct AppManifest {
     struct AppLocation location;
     /** Bitmask of AppManifestFlags. Most apps should leave this 0. */
     uint8_t flags;
+    /** Stack allocation config for this app's task. */
+    struct AppStackConfig stack;
 };
 
+bool app_id_is_valid(const char* id);
+
 #ifdef __cplusplus
 }
 #endif

Modules/app-module/include/app/metadata.h

@@ -50,6 +50,12 @@ struct AppMetadata {
      * Must be NULL-terminated.
      */
     char requires_device_id[APP_METADATA_REQUIRES_DEVICE_ID_LENGTH + 1];
+
+    /**
+     * Stack depth (in words) for the app's task. Optional; 0 means scheduler default.
+     * @warning Avoid default values: the default is conservative, which wastes memory.
+     */
+    uint32_t stack_depth;
 };
 
 /**