Scope sub-third-parties per parent

Replace the many-to-many junction table with a direct
parent_third_party_id foreign key on third_parties. Each
sub-third-party now belongs to exactly one parent, making
duplicates across parents independent entities.

Replace the firstLevel boolean with an integer level field
(1 = direct, 2+ = parent level + 1) to support arbitrary
nesting depth.

Remove the createThirdPartyThirdPartyMapping and
deleteThirdPartyThirdPartyMapping mutations, the CLI
link/unlink commands, and the corresponding MCP tools.
Creating a child third party now just requires passing
parentThirdPartyId on the existing createThirdParty mutation.

The frontend walks the parentThirdParty chain to build
display names like "Name (Ancestor1/Ancestor2)" and shows
clickable ancestor links on the detail page.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/server/api/console/v1/graphql/third_party.graphql

@@ -198,7 +198,7 @@ input ThirdPartyOrder
 }
 
 input ThirdPartyFilter {
-    firstLevel: Boolean
+    level: Int
     query: String
 }
 
@@ -303,7 +303,10 @@ type ThirdParty implements Node {
     legalName: String
     websiteUrl: String
     showOnTrustCenter: Boolean!
-    firstLevel: Boolean!
+    level: Int!
+
+    parentThirdParty: ThirdParty @goField(forceResolver: true)
+    ancestors: [ThirdParty!]! @goField(forceResolver: true)
 
     childThirdParties(
         first: Int
@@ -506,12 +509,6 @@ extend type Mutation {
     publishThirdPartyList(
         input: PublishThirdPartyListInput!
     ): PublishThirdPartyListPayload!
-    createThirdPartyThirdPartyMapping(
-        input: CreateThirdPartyThirdPartyMappingInput!
-    ): CreateThirdPartyThirdPartyMappingPayload!
-    deleteThirdPartyThirdPartyMapping(
-        input: DeleteThirdPartyThirdPartyMappingInput!
-    ): DeleteThirdPartyThirdPartyMappingPayload!
 }
 
 input PublishThirdPartyListInput {
@@ -546,7 +543,7 @@ input CreateThirdPartyInput {
     termsOfServiceUrl: String
     businessOwnerId: ID
     securityOwnerId: ID
-    firstLevel: Boolean
+    parentThirdPartyId: ID
 }
 
 input UpdateThirdPartyInput {
@@ -571,7 +568,6 @@ input UpdateThirdPartyInput {
     businessOwnerId: ID @goField(omittable: true)
     securityOwnerId: ID @goField(omittable: true)
     showOnTrustCenter: Boolean
-    firstLevel: Boolean
 }
 
 input DeleteThirdPartyInput {
@@ -755,21 +751,3 @@ type CreateThirdPartyRiskAssessmentPayload {
 type VetThirdPartyPayload {
     thirdParty: ThirdParty!
 }
-
-input CreateThirdPartyThirdPartyMappingInput {
-    parentThirdPartyId: ID!
-    childThirdPartyId: ID!
-}
-
-type CreateThirdPartyThirdPartyMappingPayload {
-    thirdPartyEdge: ThirdPartyEdge!
-}
-
-input DeleteThirdPartyThirdPartyMappingInput {
-    parentThirdPartyId: ID!
-    childThirdPartyId: ID!
-}
-
-type DeleteThirdPartyThirdPartyMappingPayload {
-    removedThirdPartyId: ID!
-}