Three related fixes so the brain DB works on Postgres, not just MariaDB:
1. config.php — brain charset/collation was hardcoded to utf8mb4 which
Postgres rejects as client_encoding. Now driver-aware: utf8 for
pgsql, utf8mb4 otherwise. Override via BRAIN_DB_CHARSET env var.
2. Migration 000008 (create_brain_memories) — self-referential FK on
supersedes_id was declared inside Schema::create{}, causing Postgres
to evaluate it before the PK index existed ('no unique constraint
matching given keys'). Split into Schema::create + separate
Schema::table to guarantee PK is in place when FK is added.
3. Migration 000009 (drop workspace FK) — try/catch inside the Blueprint
closure couldn't catch deferred SQL failures. Replaced with a
constraint-exists pre-query against information_schema, supporting
both pgsql and mariadb/mysql drivers. Fresh installs no longer fail
trying to drop a constraint that was never created.
Co-Authored-By: Virgil <virgil@lethean.io>
