Implement posix app loading (#643)

- Added POSIX desktop support for SDK builds, application packaging, and integration testing.
- Added POSIX filesystem partitions and improved application path handling.
- Added simulator support for loading and running applications dynamically.
- Improved simulator task stack handling and display startup reliability.
- Improved simulator display scaling, resizing, high-DPI support, and pointer accuracy.
- Fixed LVGL timers and input polling on POSIX. (fixes simulator with Linux on some Intel graphics platforms)
- Standardized data paths across platforms.
- Logging now works via separate task: this allows apps to write to log without it affecting their stdout (for apps that output text as relevant date for other apps, like the File Selection app)
- Fixes for app stdio

TactilityKernel/private/tactility/log_queue.h

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Fixed capacity of one queued log line (256 bytes * 24-deep queue = 6KB, negligible against the
+// hundreds of KB of free heap typically available - generous enough to hold a full log line with
+// color/timestamp/tag prefix plus a realistic message, e.g. a full SD-card path in an error log).
+#define LOG_QUEUE_MESSAGE_MAX_LENGTH 256U
+
+/**
+ * Starts the shared log queue and its dedicated drain (writer) task. Idempotent - safe to call
+ * more than once (only the first call has any effect). Must be called as early as possible in
+ * boot - see kernel_init.cpp, which calls this as its very first statement.
+ */
+void log_queue_init(void);
+
+/**
+ * Enqueues an already-fully-formatted, ready-to-write log line (NOT a printf-style format
+ * string) so the dedicated drain task can write it via a path that never goes through
+ * app-module's fd-table redirection (see Modules/app-module/source/io.cpp's app_io_write()) -
+ * this is the ONLY function log-producing code should call to reach the console; it must never
+ * itself call write()/printf()/etc, since those would be intercepted whenever called from an app
+ * instance's own task, which is exactly the bug this exists to structurally prevent.
+ *
+ * Non-blocking: if the queue is full, the message is dropped and a counter is incremented; the
+ * drain task prepends a "N messages dropped" notice before its next write. If called before
+ * log_queue_init() has run, performs a direct synchronous write instead of enqueueing - safe,
+ * since no app instance (and so no fd-table redirection) can exist yet that early in boot.
+ * Truncates messages longer than LOG_QUEUE_MESSAGE_MAX_LENGTH - 1.
+ */
+void log_queue_write(const char* data, size_t length);
+
+#ifdef __cplusplus
+}
+#endif