[Feature Request] Forward URL query parameters to agent thread_context for deep-link automation

## Problem

When a user navigates to the SRE Agent web frontend with URL query parameters (e.g., `.../views/thread/{id}?bugId=12345`), the **query parameters are stripped by the frontend** and never reach the agent's `thread_context`. The agent cannot read or act on URL-embedded context.

## Current Behavior

- User navigates to: `https://sre.azure.com/.../views/thread/{id}?bugId=12345&action=triage`
- The browser address bar shows the full URL with query params
- The SRE Agent frontend sends only the canonical URL to the backend — query params are **not forwarded**
- The agent's `thread_context` receives: `https://sre.azure.com/.../views/thread/{id}` (no params)
- Confirmed by testing (May 2026)

## Proposed Solution

The SRE Agent web UI frontend should read `window.location.search` and include all query parameters in the context payload sent to the agent backend. Options:

1. **Append to `thread_context`** — include the full URL with query params in the existing `thread_context` field
2. **New `url_params` field** — add a dedicated field in the context payload for structured query parameters (key-value pairs)
3. **Both** — full URL in `thread_context` + parsed params in `url_params` for easy programmatic access

This is a small frontend change — the data is already in `window.location.search`, it just needs to be passed through.

## Use Case

### One-Click Workflow Trigger from External Surfaces
Teams cards, dashboards, or emails can link directly to an SRE Agent thread with embedded context:
```
https://sre.azure.com/.../views/thread/{id}?bugId=12345
```

When the user clicks the link:
1. The agent reads the `bugId` param from `thread_context` on the first message
2. Auto-starts the relevant triage workflow
3. The user sees the investigation begin immediately — **zero typing required**

Without URL param forwarding, the user must manually type the ID after landing on the thread, breaking the one-click experience.

### Other Deep-Link Patterns
- `?resourceId=/subscriptions/.../providers/...` — pre-scope the agent to a specific Azure resource
- `?incident=INC001234` — auto-start incident investigation
- `?action=health-check` — trigger a specific workflow on thread open
- `?message=Check%20CPU%20on%20prod-app` — pre-fill the first message

## Impact

- **High** — enables true one-click automation from external surfaces (Teams cards, dashboards, emails, work items)
- Small frontend change with large workflow value
- Foundation for event-driven agent invocation from any URL-capable surface

## Environment

- Azure SRE Agent (GA)
- SRE Agent web frontend at sre.azure.com
- Tested and confirmed: params are stripped by the frontend (May 2026)

Start at the web frontend entry point that builds the agent context payload and inspect how window.location.search is handled before thread_context is sent. Compare the canonical URL with the deep-link URL, then confirm that the selected query parameters arrive in the agent context without being stripped.

Written by the indexing model from the issue text.