Add architecture docs, fix gRPC/REST API parity, project conventions

- Add ARCHITECTURE.md with full system specification
- Add Project Structure and API Sync Rule to CLAUDE.md; ignore srv/
- Fix engine.proto MountRequest missing config field
- Add pki.proto PKIService to match unauthenticated REST PKI routes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/templates/dashboard.html

@@ -14,7 +14,11 @@
     <thead><tr><th>Name</th><th>Type</th><th>Path</th></tr></thead>
     <tbody>
     {{range .Mounts}}
-    <tr><td>{{.Name}}</td><td>{{.Type}}</td><td>{{.MountPath}}</td></tr>
+    <tr>
+        <td>{{if eq (printf "%s" .Type) "ca"}}<a href="/pki">{{.Name}}</a>{{else}}{{.Name}}{{end}}</td>
+        <td>{{.Type}}</td>
+        <td>{{.MountPath}}</td>
+    </tr>
     {{end}}
     </tbody>
 </table>
@@ -23,6 +27,33 @@
 {{end}}
 
 {{if .IsAdmin}}
+<h3>Mount CA Engine</h3>
+{{if .MountError}}<div class="error">{{.MountError}}</div>{{end}}
+<form method="post" action="/dashboard/mount-ca" enctype="multipart/form-data">
+    <div class="form-row">
+        <div class="form-group">
+            <label for="mount_name">Mount Name</label>
+            <input type="text" id="mount_name" name="name" placeholder="pki" required>
+        </div>
+        <div class="form-group">
+            <label for="organization">Organization</label>
+            <input type="text" id="organization" name="organization" placeholder="Metacircular">
+        </div>
+    </div>
+    <details>
+        <summary>Import existing root CA (optional)</summary>
+        <div class="form-group">
+            <label for="cert_file">Certificate PEM file</label>
+            <input type="file" id="cert_file" name="cert_file" accept=".pem,.crt">
+        </div>
+        <div class="form-group">
+            <label for="key_file">Private Key PEM file</label>
+            <input type="file" id="key_file" name="key_file" accept=".pem,.key">
+        </div>
+    </details>
+    <button type="submit">Mount</button>
+</form>
+
 <h3>Admin Actions</h3>
 <div class="admin-actions">
     <button hx-post="/v1/seal" hx-confirm="Are you sure you want to seal the service?">Seal Service</button>