fix(data): protect portfolio publication invariant

docs/superpowers/specs/2026-05-30-completed-game-portfolio-design.md

@@ -79,6 +79,8 @@ CHECK (NOT is_public OR (
 
 Application validation additionally requires at least one linked completed session and at least one linked GM before publishing because those requirements span child tables.
 
+Database triggers on `portfolio_game_sessions` and `portfolio_game_masters` protect the same invariant after link removal. After a link is deleted, the trigger locks the parent card, checks both required link sets, and sets `is_public = false` with a fresh `updated_at` when either set is empty. It deliberately preserves `published_at` as the timestamp of the first publication. The link foreign keys retain `ON DELETE CASCADE`; when the card itself or its owning club is deleted, the trigger update is a harmless no-op for the disappearing parent row.
+
 ### `portfolio_game_sessions`
 
 | Column | Type | Constraints | Description |
@@ -125,7 +127,7 @@ UNIQUE (portfolio_game_id, author_player_id)
 ```
 
 - Partial public index on `(portfolio_game_id, created_at DESC)` where `moderation_status = 'Approved'` and `publication_consent_at IS NOT NULL`.
-- Partial moderation index on `(created_at)` where `moderation_status = 'Pending'`.
+- Partial moderation index on `(portfolio_game_id, created_at DESC)` where `moderation_status = 'Pending'`.
 
 ---
 
@@ -339,7 +341,7 @@ Follow TDD for production changes.
 
 ### Schema And Contracts
 
-- Migration source-contract tests assert the four new tables, constraints, and indexes.
+- Migration source-contract tests assert the four new tables, format constraint, publication guard, case-insensitive slug uniqueness, group and GM-profile indexes, card-oriented pending-review index, and the link-removal trigger protection.
 - Public DTO reflection/source tests assert that private identifiers and physical storage paths are absent.
 - Existing showcase tests continue to assert the future-session catalog boundary.