feat:Add google search tool

[esafwan]

Important: Merge after merging liteLLM PR.

Add Google Search Tool

Adds Google Programmable Search Engine (PSE) support as a tool via LiteLLM.

• Implements Google Search tool in SDK tools
• Integrates with LiteLLM unified provider
• Adds configuration and error handling

### How to Add and Configure Google Search API Key in Frappe

#### Step 1: Add Keys in Site Config

The Google Search tool uses credentials stored in `site_config.json`. You need to add:

* `google_pse_api_key` → your Google Programmable Search API key
* `google_pse_engine_id` → your Google Custom Search Engine ID


~~~json
{
  "google_pse_api_key": "YOUR_API_KEY_HERE",
  "google_pse_engine_id": "YOUR_ENGINE_ID_HERE"
}
~~~

#### Step 2: Get Your Google API Credentials

1. Go to [[Google Cloud Console](https://console.cloud.google.com/)](https://console.cloud.google.com/)
2. Create/select a project
3. Enable **Custom Search API**
4. Under **APIs & Services → Credentials**, create an API key → this is `google_pse_api_key`
5. Visit [[Programmable Search Engine](https://programmablesearchengine.google.com/)](https://programmablesearchengine.google.com/)
6. Create or open your search engine
7. Copy the **Search Engine ID** → this is `google_pse_engine_id`

Once added, the tool automatically detects these values from `site_config` — no restart required.

[esafwan]

Closing — superseded by #439, which re-implements Google Search as an Agent Tool Function type against current develop (this branch targets the pre-rename agentflo/ tree and cannot be rebased; the LiteLLM prerequisite it mentions has long since landed). Same configuration surface: google_pse_api_key + google_pse_engine_id in site_config.json.