feat(proxy): sync proxy_referrals.py from deploy; expose via API

The deploy at /srv/pry/ had a thin proxy_referrals.py with 5 curated
proxy provider affiliate entries (Bright Data, Oxylabs, Smartproxy,
IPRoyal, Webshare). The repo was missing this file, so deploy and repo
were out of sync.

Changes:
- Add proxy_referrals.py (MIT) with the 5-provider curated catalog
- proxy_manager.py: import PROVIDER_REFERRALS, add 4 helper methods:
    get_proxy_referral(tag)
    get_proxy_referral_url(tag)
    list_proxy_referrals()
    get_proxy_referral_summary() - per-tier breakdown
- api.py: expose 2 new endpoints
    GET /v1/proxy/referrals          - full catalog + summary
    GET /v1/proxy/referrals/{tag}    - single provider
- 12/12 existing proxy_manager tests still pass
- Total routes: 195 -> 197

api.py

@@ -4132,6 +4132,40 @@ async def proxy_signup(provider: str = Body(...)) -> dict[str, Any]:
     url = pm.get_signup_link(provider)
     return {"success": True, "data": {"signup_url": url, "provider": provider}}
 
+@app.get("/v1/proxy/referrals", tags=["Proxy"], summary="List proxy provider affiliate referrals")
+async def list_proxy_referrals() -> dict[str, Any]:
+    """Return the curated proxy provider affiliate catalog (proxy_referrals.py).
+
+    This is the marketing-friendly subset: commission, promo codes, tier
+    (premium/standard/budget), and referral URLs. Useful for a "Sign up via Pry
+    and we get a cut" UI, or for showing users premium options when their free
+    proxy fails.
+
+    The full connection metadata (host, port, auth) lives in /v1/proxy/providers.
+    """
+    from proxy_manager import ProxyManager
+
+    pm = ProxyManager()
+    return {
+        "success": True,
+        "data": {
+            "providers": pm.list_proxy_referrals(),
+            "summary": pm.get_proxy_referral_summary(),
+        },
+    }
+
+
+@app.get("/v1/proxy/referrals/{tag}", tags=["Proxy"], summary="Get a single proxy provider referral")
+async def get_proxy_referral(tag: str) -> dict[str, Any]:
+    """Return the affiliate info for a single proxy provider by tag."""
+    from proxy_manager import ProxyManager
+
+    pm = ProxyManager()
+    info = pm.get_proxy_referral(tag)
+    if not info:
+        return {"success": False, "error": f"No proxy referral found for tag: {tag}"}
+    return {"success": True, "data": {"tag": tag, **info}}
+
 
 @app.post("/v1/proxy/configure", tags=["Proxy"], summary="Configure proxy credentials")
 async def proxy_configure(