#196 Apps: Database migrations for app system tables

## Parent Epic: #195 ## Description Create database migrations for the app system tables. ## Tables to Create ### 1. highway.apps Core app registry table with fields: - app_id (UUID PK) - app_name, publisher_id (unique together) - display_name, description, icon_url, documentation_url - category, tags (JSONB), visibility - is_verified, is_builtin, status - timestamps and created_by ### 2. highway.app_versions Immutable version snapshots: - version_id (UUID PK) - app_id (FK), version (semver) - version_major/minor/patch/prerelease - definition_hash, definition (JSONB) - entrypoint_type, entrypoint_config (JSONB) - required_permissions, required_secrets, configuration_schema (JSONB) - actions (JSONB) - exposed methods - status (draft/published/deprecated) - changelog, breaking_changes, migration_guide ### 3. highway.tenant_app_installations Per-tenant installations: - installation_id (UUID PK) - tenant_id, app_id (FK), version_id (FK) - auto_update, update_channel - configuration, secrets_config (JSONB) - status, usage tracking - timestamps ### 4. highway.app_execution_log (partitioned) Audit trail for app executions: - Partitioned by created_at - tenant_id, workflow_run_id, task_id - app_id, version_id, action_name - status, timing, I/O summaries, errors - tracing fields ## Migration File engine/migrations/sql/highway_0.0.60_apps.sql ## Indexes Required - All foreign keys indexed - Composite indexes for common queries - GIN indexes for JSONB search - Partial indexes for active/enabled records ## Testing - Migration applies cleanly - Rollback works - FK constraints enforced - Unique constraints work