feat(server): converge legacy compatibility (#15426)

#### PR Dependency Tree


* **PR #15426** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added workspace BYOK profiles with provider/model catalogs, capability
validation, connection probing, credential rotation, reordering, and
secure local leases.
* Added Copilot route options, selectable targets, managed tiers,
explicit profile/model overrides, and improved streaming with tool
callbacks and abort support.
* Added Copilot availability controls to prevent access when the feature
is disabled.
* **Changes**
* Simplified Copilot configuration and removed legacy provider-specific
settings.
* Removed obsolete model, token-cost, transcript strategy, and provider
metadata fields from public responses.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/migrations/20260803095500_converge_copilot_runtime/migration.sql

@@ -0,0 +1,58 @@
+DELETE FROM "app_configs"
+WHERE "id" IN (
+  'copilot.providers.openai',
+  'copilot.providers.cloudflareWorkersAi',
+  'copilot.providers.fal',
+  'copilot.providers.gemini',
+  'copilot.providers.geminiVertex',
+  'copilot.providers.anthropic',
+  'copilot.providers.anthropicVertex',
+  'copilot.providers.defaults'
+);
+
+DELETE FROM "ai_workspace_byok_configs";
+
+DO $$
+BEGIN
+  IF to_regclass('public.runtime_states') IS NOT NULL THEN
+    DELETE FROM "runtime_states"
+    WHERE "purpose" IN (
+      'copilot_byok_local_lease',
+      'copilot_byok_local_lease:active'
+    );
+  END IF;
+END $$;
+
+ALTER TABLE "ai_workspace_byok_configs"
+  DROP COLUMN "endpoint",
+  DROP COLUMN "disabled_reason",
+  DROP COLUMN "last_validated_at",
+  DROP COLUMN "last_validation_error",
+  ADD COLUMN "definition" JSONB NOT NULL,
+  ADD COLUMN "revision" INTEGER NOT NULL DEFAULT 1,
+  ADD COLUMN "credential_generation" INTEGER NOT NULL DEFAULT 1,
+  ADD COLUMN "validation" JSONB;
+
+ALTER TABLE "ai_sessions_metadata"
+  DROP CONSTRAINT "ai_sessions_metadata_prompt_name_fkey",
+  DROP COLUMN "tokenCost";
+
+UPDATE "ai_action_runs"
+SET "action_id" = 'transcript.audio'
+WHERE "action_id" = 'transcript.audio.gemini';
+
+UPDATE "ai_transcript_tasks"
+SET
+  "recipe_id" = 'transcript.audio',
+  "input_snapshot" = "input_snapshot"::jsonb - 'providerMeta' - 'strategy',
+  "public_meta" = "public_meta"::jsonb - 'providerMeta' - 'strategy',
+  "protected_result" = "protected_result"::jsonb - 'providerMeta' - 'strategy'
+WHERE "recipe_id" = 'transcript.audio.gemini';
+
+ALTER TABLE "ai_transcript_tasks"
+  DROP COLUMN "strategy";
+
+DROP TABLE "ai_prompts_messages";
+DROP TABLE "ai_prompts_metadata";
+
+ALTER TYPE "AiPromptRole" RENAME TO "AiSessionMessageRole";