feat: add get_shape_library tool for AI icon discovery (#335)

* feat: add get_shape_library tool for AI icon discovery

- Add server-side tool that returns shape library documentation
- AI can fetch icon/shape names on-demand before generating diagrams
- Includes path traversal protection and input sanitization
- Library index embedded in tool description for discoverability
- Supports 33 libraries: AWS, Azure, GCP, Kubernetes, Cisco, etc.

* fix: improve get_shape_library error handling and imports

- Move fs/path imports to top of file (avoid dynamic imports per call)
- Distinguish file-not-found vs other errors in catch block
- Include invalid input in validation error message
- Log unexpected errors for debugging

* docs: add get_shape_library to system prompt tool list

- Add Tool4 (get_shape_library) to available tools section
- Add usage guidance in 'Choose the right tool' section
- Update AWS icons note to reference get_shape_library for icon discovery

* fix: display get_shape_library tool output in chat UI

* fix: correct state check for get_shape_library output display

* fix: make get_shape_library output respect fold state

* style: auto-format with Biome

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

components/chat-message-display.tsx

@@ -634,6 +634,8 @@ export function ChatMessageDisplay({
                     return "Generate Diagram"
                 case "edit_diagram":
                     return "Edit Diagram"
+                case "get_shape_library":
+                    return "Get Shape Library"
                 default:
                     return name
             }
@@ -728,6 +730,25 @@ export function ChatMessageDisplay({
                             </div>
                         )
                     })()}
+                {/* Show get_shape_library output on success */}
+                {output &&
+                    toolName === "get_shape_library" &&
+                    state === "output-available" &&
+                    isExpanded && (
+                        <div className="px-4 py-3 border-t border-border/40">
+                            <div className="text-xs text-muted-foreground mb-2">
+                                Library loaded (
+                                {typeof output === "string" ? output.length : 0}{" "}
+                                chars)
+                            </div>
+                            <pre className="text-xs bg-muted/50 p-2 rounded-md overflow-auto max-h-32 whitespace-pre-wrap">
+                                {typeof output === "string"
+                                    ? output.substring(0, 800) +
+                                      (output.length > 800 ? "\n..." : "")
+                                    : String(output)}
+                            </pre>
+                        </div>
+                    )}
             </div>
         )
     }