feat: Hermit 1.1.0 — HERMIT_* env, Tauri desktop shell

Wire hermit_getenv across the engine, rebrand WebUI/systemd/docs, and
add apps/desktop (Tauri 2 + React) with a DeepSeek-Harness-like UI.
Qt app/ is frozen; full libcstcore FFI is scaffolded behind --features engine.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/DEPRECATED.md

@@ -0,0 +1,10 @@
+# Deprecated: Qt front end
+
+This directory is the **legacy Qt 6 / QML** Hermit GUI (`cst-agent-app`).
+
+The supported desktop shell is **`apps/desktop`** (Tauri 2 + React), with a
+DeepSeek-Harness-inspired layout and an in-process C engine bridge.
+
+Do not add features here. Once Tauri reaches feature parity, this tree will be
+moved to `archive/qt-app` or removed. Android APK scripts that target this tree
+are transitional.

app/src/core/AgentCore.cpp

@@ -143,7 +143,9 @@ bool AgentCore::open(const QString &workspace, const QString &provider,
   if (m_cfg.api_key[0] == 0 && m_cfg.provider[0]) {
     char key[512] = "";
     if (cst_creds_resolve(m_cfg.provider, key, sizeof(key), nullptr) != 0) {
-      const char *env = getenv("CST_API_KEY");
+      const char *env = getenv("HERMIT_API_KEY");
+      if (!env || !env[0])
+        env = getenv("CST_API_KEY");
       if (env && env[0])
         snprintf(key, sizeof(key), "%s", env);
     }