Implement UI scaling and more (#501)

**New Features**
 * Runtime font accessors and new symbol fonts for text, launcher, statusbar, and shared icons.
 * Added font height base setting to device.properties
 * Text fonts now have 3 sizes: small, default, large

**Improvements**
 * Renamed `UiScale` to `UiDensity`
 * Statusbar, toolbar and many UI components now compute heights and spacing from fonts/density.
 * SSD1306 initialization sequence refined for more stable startup.
 * Multiple image assets replaced by symbol-font rendering.
 * Many layout improvements related to density, font scaling and icon scaling
 * Updated folder name capitalization for newer style

TactilityKernel/source/module.cpp

@@ -0,0 +1,118 @@
+#include <cstring>
+#include <algorithm>
+#include <new>
+#include <tactility/concurrent/mutex.h>
+#include <tactility/module.h>
+#include <vector>
+
+#define TAG "module"
+
+struct ModuleInternal {
+    bool started = false;
+};
+
+struct ModuleLedger {
+    std::vector<struct Module*> modules;
+    struct Mutex mutex {};
+
+    ModuleLedger() { mutex_construct(&mutex); }
+    ~ModuleLedger() { mutex_destruct(&mutex); }
+};
+
+static ModuleLedger ledger;
+
+extern "C" {
+
+error_t module_construct(struct Module* module) {
+    module->internal = new (std::nothrow) ModuleInternal();
+    if (module->internal == nullptr) return ERROR_OUT_OF_MEMORY;
+    return ERROR_NONE;
+}
+
+error_t module_destruct(struct Module* module) {
+    delete static_cast<ModuleInternal*>(module->internal);
+    module->internal = nullptr;
+    return ERROR_NONE;
+}
+
+error_t module_add(struct Module* module) {
+    mutex_lock(&ledger.mutex);
+    ledger.modules.push_back(module);
+    mutex_unlock(&ledger.mutex);
+    return ERROR_NONE;
+}
+
+error_t module_remove(struct Module* module) {
+    mutex_lock(&ledger.mutex);
+    ledger.modules.erase(std::remove(ledger.modules.begin(), ledger.modules.end(), module), ledger.modules.end());
+    mutex_unlock(&ledger.mutex);
+    return ERROR_NONE;
+}
+
+error_t module_start(struct Module* module) {
+    LOG_I(TAG, "start %s", module->name);
+
+    auto* internal = static_cast<ModuleInternal*>(module->internal);
+    if (internal->started) return ERROR_NONE;
+
+    error_t error = module->start();
+    internal->started = (error == ERROR_NONE);
+    return error;
+}
+
+bool module_is_started(struct Module* module) {
+    return static_cast<ModuleInternal*>(module->internal)->started;
+}
+
+error_t module_stop(struct Module* module) {
+    LOG_I(TAG, "stop %s", module->name);
+
+    auto* internal = static_cast<ModuleInternal*>(module->internal);
+    if (!internal->started) return ERROR_NONE;
+
+    error_t error = module->stop();
+    if (error != ERROR_NONE) {
+        return error;
+    }
+
+    internal->started = false;
+    return error;
+}
+
+error_t module_construct_add_start(struct Module* module) {
+    error_t error = module_construct(module);
+    if (error != ERROR_NONE) return error;
+    error = module_add(module);
+    if (error != ERROR_NONE) return error;
+    return module_start(module);
+}
+
+bool module_resolve_symbol(Module* module, const char* symbol_name, uintptr_t* symbol_address) {
+    if (!module_is_started(module)) return false;
+    auto* symbol_ptr = module->symbols;
+    if (symbol_ptr == nullptr) return false;
+    while (symbol_ptr->name != nullptr) {
+        if (strcmp(symbol_ptr->name, symbol_name) == 0) {
+            *symbol_address = reinterpret_cast<uintptr_t>(symbol_ptr->symbol);
+            return true;
+        }
+        symbol_ptr++;
+    }
+    return false;
+}
+
+bool module_resolve_symbol_global(const char* symbol_name, uintptr_t* symbol_address) {
+    mutex_lock(&ledger.mutex);
+    for (auto* module : ledger.modules) {
+        if (!module_is_started(module))
+            continue;
+        if (module_resolve_symbol(module, symbol_name, symbol_address)) {
+            mutex_unlock(&ledger.mutex);
+            return true;
+        }
+    }
+    mutex_unlock(&ledger.mutex);
+    return false;
+}
+
+}