fix(backend): pass credential type from SDK registry to integrations API (#11544)

### Changes 🏗️

This PR improves the `/integrations/providers` endpoint to dynamically
determine supported authentication types from the SDK registry instead
of using hardcoded values.

**What changed:**
- The `list_providers` function now looks up each provider in the
`AutoRegistry` to get its `supported_auth_types`
- If a provider has defined auth types in the SDK registry, those are
used to set `supports_api_key`, `supports_user_password`, and
`supports_host_scoped` flags
- Falls back to legacy hardcoded behavior for providers not registered
in the SDK (maintains backwards compatibility)

**Why:**
- Providers can now correctly declare their supported authentication
methods via the SDK
- Removes brittle hardcoded checks like `name in ("smtp",)` for specific
providers
- Makes the credential type system more extensible and maintainable

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
- [x] Verified providers with SDK-defined auth types return correct
flags
  - [x] Verified legacy providers still work with fallback behavior
- [x] Tested the `/integrations/providers` endpoint returns expected
data

#### For configuration changes:

- [x] `.env.default` is updated or already compatible with my changes
- [x] `docker-compose.yml` is updated or already compatible with my
changes
- [x] I have included a list of my configuration changes in the PR
description (under **Changes**)

No configuration changes required for this PR.

autogpt_platform/backend/backend/server/external/routes/integrations.py

@@ -273,6 +273,8 @@ async def list_providers(
     except Exception as e:
         logger.warning(f"Failed to load blocks: {e}")
 
+    from backend.sdk.registry import AutoRegistry
+
     providers = []
     for name in get_all_provider_names():
         supports_oauth = name in HANDLERS_BY_NAME
@@ -281,13 +283,27 @@ async def list_providers(
             getattr(handler_class, "DEFAULT_SCOPES", []) if handler_class else []
         )
 
+        # Check if provider has specific auth types from SDK registration
+        sdk_provider = AutoRegistry.get_provider(name)
+        if sdk_provider and sdk_provider.supported_auth_types:
+            supports_api_key = "api_key" in sdk_provider.supported_auth_types
+            supports_user_password = (
+                "user_password" in sdk_provider.supported_auth_types
+            )
+            supports_host_scoped = "host_scoped" in sdk_provider.supported_auth_types
+        else:
+            # Fallback for legacy providers
+            supports_api_key = True  # All providers can accept API keys
+            supports_user_password = name in ("smtp",)
+            supports_host_scoped = name == "http"
+
         providers.append(
             ProviderInfo(
                 name=name,
                 supports_oauth=supports_oauth,
-                supports_api_key=True,  # All providers can accept API keys
-                supports_user_password=name in ("smtp",),  # SMTP uses user/password
-                supports_host_scoped=name == "http",  # HTTP block uses host-scoped
+                supports_api_key=supports_api_key,
+                supports_user_password=supports_user_password,
+                supports_host_scoped=supports_host_scoped,
                 default_scopes=default_scopes,
             )
         )