refactor: unify project structure, improve security, and enhance deployment

- Fix WireGuard private key leak in API responses and config updates
- Update systemd service to serve from repo root with adjusted sandbox
- Add CLI flags, idempotency, and dev mode to install.sh
- Extract common utilities to lib/common.py and webui/api/common.py
- Migrate frontend to htmx for simpler, more maintainable UI
- Update docs to reflect current architecture and deployment model
- Vendor htmx dependencies per project requirements

webui/templates/proxy.html

@@ -9,7 +9,8 @@
     </div>
     <div class="flex gap-2">
         <button class="btn btn-primary" onclick="openModal('add-domain-modal')">+ Add Domain</button>
-        <button class="btn btn-outline" hx-post="/api/proxy/apply" hx-swap="none" hx-on::after-request="if(evt.detail.successful) showSuccessToast('Nginx reloaded')">Apply Changes (Reload Nginx)</button>
+                <button class="btn btn-outline" hx-post="/api/proxy/ssl-apply" hx-swap="none" hx-on::after-request="if(evt.detail.successful) showSuccessToast('SSL settings applied')">Apply SSL Settings</button>
+                <button class="btn btn-outline" hx-post="/api/proxy/apply" hx-swap="none" hx-on::after-request="if(evt.detail.successful) showSuccessToast('Nginx reloaded')">Apply Changes (Reload Nginx)</button>
     </div>
 </div>
 
@@ -76,7 +77,7 @@
 <div class="modal-overlay" id="add-domain-modal" onclick="if(event.target===this) closeModal('add-domain-modal')">
     <div class="modal">
         <h2>Add Proxy Domain</h2>
-        <form hx-post="/api/proxy/domains" hx-swap="none" hx-on::after-request="if(evt.detail.successful){ closeModal('add-domain-modal'); refreshTable('/api/proxy/domains', document.getElementById('domain-rows'), renderDomains); showSuccessToast('Domain added'); }">
+        <form hx-post="/api/proxy/domains" hx-encoding="json" hx-swap="none" hx-on::after-request="if(evt.detail.successful){ closeModal('add-domain-modal'); refreshTable('/api/proxy/domains', document.getElementById('domain-rows'), renderDomains); showSuccessToast('Domain added'); }">
             <div class="form-group">
                 <label for="new-domain">Domain</label>
                 <input type="text" id="new-domain" name="domain" placeholder="example.com" required>