feat(ui): add app launcher and NomadNet MVP

lib/tdeck_ui/UI/LXMF/NomadNetUrl.cpp

@@ -0,0 +1,50 @@
+#include "NomadNetUrl.h"
+
+#include <algorithm>
+#include <cctype>
+
+namespace UI::LXMF::NomadNet {
+
+bool Url::parse(const std::string& input, Url& result, std::string& error,
+                const std::string& current_destination) {
+    error.clear();
+    if (input.empty() || input.size() > 512) {
+        error = "Address is empty or too long";
+        return false;
+    }
+    for (unsigned char c : input) {
+        if (c < 0x20 || c == 0x7f) {
+            error = "Address contains control characters";
+            return false;
+        }
+    }
+    const auto colon = input.find(':');
+    if (colon != std::string::npos && input.find(':', colon + 1) != std::string::npos) {
+        error = "Address has too many separators";
+        return false;
+    }
+    std::string destination = colon == std::string::npos ? input : input.substr(0, colon);
+    std::string path = colon == std::string::npos ? DEFAULT_PATH : input.substr(colon + 1);
+    if (destination.empty()) destination = current_destination;
+    if (destination.size() != 32 ||
+        !std::all_of(destination.begin(), destination.end(), [](unsigned char c) { return std::isxdigit(c); })) {
+        error = "Destination must be exactly 32 hexadecimal characters";
+        return false;
+    }
+    std::transform(destination.begin(), destination.end(), destination.begin(),
+                   [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
+    if (path.empty()) path = DEFAULT_PATH;
+    if (path.front() != '/') {
+        error = "Path must begin with /";
+        return false;
+    }
+    if (path.rfind("/file/", 0) == 0) {
+        error = "Downloads are not supported in this MVP";
+        return false;
+    }
+    result.destination_hex = std::move(destination);
+    result.path = std::move(path);
+    return true;
+}
+
+} // namespace UI::LXMF::NomadNet