feat(agents): add static_headers and extra_headers fields to schema and types

Add two new fields to LiteLLM_AgentsTable:
- static_headers (Json): admin-configured headers always sent to the backend agent
- extra_headers (String[]): header names to extract from the client request and forward

Extend AgentConfig, PatchAgentRequest, and AgentResponse with the same fields.
Also remove duplicate spec_path field from LiteLLM_MCPServerTable.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

litellm/proxy/schema.prisma

@@ -63,6 +63,8 @@ model LiteLLM_AgentsTable {
   agent_name String @unique
   litellm_params Json?
   agent_card_params Json
+  static_headers       Json?          @default("{}")
+  extra_headers        String[]       @default([])
   agent_access_groups String[]       @default([])
   object_permission_id String?
   object_permission LiteLLM_ObjectPermissionTable? @relation(fields: [object_permission_id], references: [object_permission_id])
@@ -305,7 +307,6 @@ model LiteLLM_MCPServerTable {
   registration_url   String?
   allow_all_keys Boolean @default(false)
   available_on_public_internet Boolean @default(true)
-  spec_path             String?
   is_byok               Boolean  @default(false)
   byok_description      String[] @default([])
   byok_api_key_help_url String?

litellm/types/agents.py

@@ -179,6 +179,8 @@ class AgentConfig(TypedDict, total=False):
     agent_card_params: Required[AgentCard]
     litellm_params: Dict[str, Any]  # allow for any future litellm params
     object_permission: AgentObjectPermission
+    static_headers: Optional[Dict[str, str]]
+    extra_headers: Optional[List[str]]
 
 
 class PatchAgentRequest(TypedDict, total=False):
@@ -186,6 +188,8 @@ class PatchAgentRequest(TypedDict, total=False):
     agent_card_params: AgentCard
     litellm_params: Dict[str, Any]
     object_permission: AgentObjectPermission
+    static_headers: Optional[Dict[str, str]]
+    extra_headers: Optional[List[str]]
 
 
 # Request/Response models for CRUD endpoints
@@ -197,6 +201,8 @@ class AgentResponse(BaseModel):
     litellm_params: Optional[Dict[str, Any]] = None
     agent_card_params: Dict[str, Any]
     object_permission: Optional[Dict[str, Any]] = None
+    static_headers: Optional[Dict[str, str]] = None
+    extra_headers: Optional[List[str]] = None
     created_at: Optional[datetime] = None
     updated_at: Optional[datetime] = None
     created_by: Optional[str] = None