feat: add site assistant component for guided tool selection

- Introduced SiteAssistant component to assist users in selecting the right tools based on their queries.
- Integrated assistant into the main App component.
- Implemented message handling and storage for user-assistant interactions.
- Added quick prompts for common user queries related to tools.
- Enhanced ToolLandingPage and DownloadButton components with SharePanel for sharing tool results.
- Updated translations for new assistant features and sharing options.
- Added API methods for chat functionality with the assistant, including streaming responses.

backend/app/services/openrouter_config_service.py

@@ -0,0 +1,37 @@
+"""Shared OpenRouter configuration access for all AI-enabled services."""
+from dataclasses import dataclass
+import os
+
+from flask import current_app, has_app_context
+
+
+DEFAULT_OPENROUTER_MODEL = "stepfun/step-3.5-flash:free"
+DEFAULT_OPENROUTER_BASE_URL = "https://openrouter.ai/api/v1/chat/completions"
+
+
+@dataclass(frozen=True)
+class OpenRouterSettings:
+    api_key: str
+    model: str
+    base_url: str
+
+
+def get_openrouter_settings() -> OpenRouterSettings:
+    """Return the effective OpenRouter settings for the current execution context."""
+    if has_app_context():
+        api_key = str(current_app.config.get("OPENROUTER_API_KEY", "")).strip()
+        model = str(
+            current_app.config.get("OPENROUTER_MODEL", DEFAULT_OPENROUTER_MODEL)
+        ).strip() or DEFAULT_OPENROUTER_MODEL
+        base_url = str(
+            current_app.config.get("OPENROUTER_BASE_URL", DEFAULT_OPENROUTER_BASE_URL)
+        ).strip() or DEFAULT_OPENROUTER_BASE_URL
+        return OpenRouterSettings(api_key=api_key, model=model, base_url=base_url)
+
+    return OpenRouterSettings(
+        api_key=os.getenv("OPENROUTER_API_KEY", "").strip(),
+        model=os.getenv("OPENROUTER_MODEL", DEFAULT_OPENROUTER_MODEL).strip()
+        or DEFAULT_OPENROUTER_MODEL,
+        base_url=os.getenv("OPENROUTER_BASE_URL", DEFAULT_OPENROUTER_BASE_URL).strip()
+        or DEFAULT_OPENROUTER_BASE_URL,
+    )