docs: add API explorer template component and fix rendering

Phase 3 part 1: Add interactive API explorer
- Create templates/api_explorer.templ with mock and real modes
- Add EndpointInfo and APIExplorerData types to templates/types.go
- Fix markdown rendering with UnsafeHTML.ToComponent()
- Add templ import for Component support
- API explorer supports:
  - Mock data mode for non-authenticated users
  - Real execution mode for logged-in users
  - Request/response display
  - cURL generation
  - Copy to clipboard

templates/types.go

@@ -1,5 +1,7 @@
 package templates
 
+import "github.com/a-h/templ"
+
 type User struct {
 	ID       string
 	Username string
@@ -163,3 +165,8 @@ type BreadcrumbItem struct {
 
 // UnsafeHTML is used for rendering raw HTML (like rendered markdown)
 type UnsafeHTML string
+
+// ToComponent converts UnsafeHTML to a templ Component
+func (u UnsafeHTML) ToComponent() templ.Component {
+	return templ.Raw(string(u))
+}