Add custom OpenAI- and Anthropic-compatible providers

New 'Custom OpenAI-compatible' and 'Custom Anthropic-compatible' providers let
an agent run against any compatible endpoint by base URL + key: the turn posts
Chat Completions (/chat/completions) or Anthropic Messages (/v1/messages) at the
configured base URL. Backfilled into existing orgs by migration 037.

AgentCompany-New/src/main/database/migrations/037-custom-providers.ts

@@ -0,0 +1,12 @@
+export const customProvidersSchema = `
+  insert or ignore into providers(id, org_id, provider_key, label, auth_type, model, credential_id, enabled, created_at)
+  select 'prv_' || lower(hex(randomblob(16))), organizations.id, 'custom-openai', 'Custom OpenAI-compatible', 'cloud', null, null, 0, datetime('now')
+  from organizations;
+
+  insert or ignore into providers(id, org_id, provider_key, label, auth_type, model, credential_id, enabled, created_at)
+  select 'prv_' || lower(hex(randomblob(16))), organizations.id, 'custom-anthropic', 'Custom Anthropic-compatible', 'cloud', null, null, 0, datetime('now')
+  from organizations;
+
+  insert into schema_migrations(version, name, applied_at)
+  values (37, 'custom_providers', datetime('now'));
+`;

AgentCompany-New/src/main/database/schema.ts

@@ -35,6 +35,7 @@ import { auditEventImmutabilitySchema } from "./migrations/033-audit-event-immut
 import { providerAuthSessionsSchema } from "./migrations/034-provider-auth-sessions";
 import { taskRunIsolationSchema } from "./migrations/035-task-run-isolation";
 import { additionalConnectorsSchema } from "./migrations/036-additional-connectors";
+import { customProvidersSchema } from "./migrations/037-custom-providers";
 
 interface Migration {
   version: number;
@@ -79,6 +80,7 @@ const MIGRATIONS: Migration[] = [
   { version: 34, name: "provider_auth_sessions", sql: providerAuthSessionsSchema },
   { version: 35, name: "task_run_isolation", sql: taskRunIsolationSchema },
   { version: 36, name: "additional_connectors", sql: additionalConnectorsSchema },
+  { version: 37, name: "custom_providers", sql: customProvidersSchema },
 ];
 
 const SCHEMA_VERSION = MIGRATIONS[MIGRATIONS.length - 1].version;