Add NebulaController, tab manager, and CEF clients

Introduce core application structure and browser management: add NebulaController and run entry (src/app/*) to centralize window, tab and CEF lifecycle logic; implement TabManager and NebulaTab (src/browser/*) for tab creation, navigation and state tracking; add URL utilities (NormalizeNavigationInput, JsonEscape) and CEF browser client glue (src/cef/browser_client.cpp/.h) to forward chrome commands and content events. Update app/main.cpp to delegate startup to nebula::app::RunNebula. Add UI assets (chrome.html, chrome.css, chrome.js, lucide, menu-popup updates) and remove obsolete nebot.html. Update CMakeLists to include new sources, add ${CMAKE_SOURCE_DIR}/src to includes and link dwmapi on Windows. Overall this refactors startup and splits responsibilities for cleaner tab and browser lifecycle handling.

src/ui/paths.cpp

@@ -0,0 +1,121 @@
+#include "ui/paths.h"
+
+#include <windows.h>
+
+#include <algorithm>
+#include <cctype>
+
+namespace nebula::ui {
+namespace {
+
+std::string WideToUtf8(const std::wstring& value) {
+    if (value.empty()) {
+        return {};
+    }
+
+    const int size = WideCharToMultiByte(
+        CP_UTF8, 0, value.data(), static_cast<int>(value.size()),
+        nullptr, 0, nullptr, nullptr);
+    std::string result(size, '\0');
+    WideCharToMultiByte(
+        CP_UTF8, 0, value.data(), static_cast<int>(value.size()),
+        result.data(), size, nullptr, nullptr);
+    return result;
+}
+
+std::string GetUrlWithoutDecoration(std::string url) {
+    const size_t split = url.find_first_of("?#");
+    if (split != std::string::npos) {
+        url.resize(split);
+    }
+    return url;
+}
+
+std::string ToLowerAscii(std::string value) {
+    std::transform(value.begin(), value.end(), value.begin(), [](unsigned char ch) {
+        return static_cast<char>(std::tolower(ch));
+    });
+    return value;
+}
+
+}  // namespace
+
+std::filesystem::path GetExecutableDirectory() {
+    wchar_t exe_path[MAX_PATH] = {};
+    const DWORD length = GetModuleFileNameW(nullptr, exe_path, MAX_PATH);
+    if (length == 0 || length == MAX_PATH) {
+        return {};
+    }
+
+    return std::filesystem::path(exe_path).parent_path();
+}
+
+std::filesystem::path GetUiPagePath(const std::wstring& page_name) {
+    const auto exe_dir = GetExecutableDirectory();
+    if (exe_dir.empty()) {
+        return {};
+    }
+
+    return exe_dir / L"ui" / L"pages" / page_name;
+}
+
+std::string FilePathToUrl(std::filesystem::path path) {
+    std::string value = WideToUtf8(path.wstring());
+    for (char& ch : value) {
+        if (ch == '\\') {
+            ch = '/';
+        }
+    }
+
+    std::string encoded;
+    encoded.reserve(value.size());
+    for (char ch : value) {
+        encoded += ch == ' ' ? "%20" : std::string(1, ch);
+    }
+    return "file:///" + encoded;
+}
+
+std::string GetChromeUrl() {
+    const auto path = GetUiPagePath(L"chrome.html");
+    return path.empty() ? GetHomeUrl() : FilePathToUrl(path);
+}
+
+std::string GetHomeUrl() {
+    const auto path = GetUiPagePath(L"home.html");
+    return path.empty() ? "https://www.google.com" : FilePathToUrl(path);
+}
+
+std::string GetSettingsUrl() {
+    const auto path = GetUiPagePath(L"settings.html");
+    return path.empty() ? GetHomeUrl() : FilePathToUrl(path);
+}
+
+std::string GetBigPictureUrl() {
+    const auto path = GetUiPagePath(L"bigpicture.html");
+    return path.empty() ? GetHomeUrl() : FilePathToUrl(path);
+}
+
+std::string GetMenuPopupUrl() {
+    const auto path = GetUiPagePath(L"menu-popup.html");
+    return path.empty() ? GetHomeUrl() : FilePathToUrl(path);
+}
+
+bool IsInternalHomeUrl(const std::string& url) {
+    return GetUrlWithoutDecoration(url) == GetHomeUrl();
+}
+
+bool IsChromiumNewTabUrl(const std::string& url) {
+    const std::string target = ToLowerAscii(GetUrlWithoutDecoration(url));
+    return target == "about:blank" ||
+           target == "chrome://newtab" ||
+           target == "chrome://newtab/" ||
+           target == "chrome://new-tab-page" ||
+           target == "chrome://new-tab-page/" ||
+           target == "chrome-search://local-ntp/local-ntp.html";
+}
+
+bool IsEmptyOrChromiumNewTabUrl(const std::string& url) {
+    return url.empty() || IsChromiumNewTabUrl(url);
+}
+
+}  // namespace nebula::ui