Adds a SQL bundle plus event triggers that enforce `INHERITS (hectic.created_at)`
on every user CREATE TABLE and auto-attach a BEFORE UPDATE row trigger when a
table inherits `hectic.updated_at`. Always-exempt: `hectic`, `information_schema`,
`pg_*`, declarative partitions, temp tables. Per-DB opt-out via the GUC
`hectic.inheritance_extra_excluded_schemas`.
Exposed three ways:
* `pkgs.hectic.hectic-inheritance` — derivation with the SQL at
$out/share/hectic/hectic-inheritance.sql
* `self.lib.hecticInheritance.{sql,path}` — pkgs-free Nix surface
* `postgres-init` opt-in via `PG_HECTIC_INHERITANCE=1` (HECTIC_INHERITANCE_SQL
overrides the default)
Test postgres-init-hectic-inheritance covers all six branches: bootstrap,
non-inheriting reject, accepting inheritance, auto updated_at trigger fires,
GUC exclusion, declarative partition exemption.
Previously when PG_REUSE=1 and PG_VERSION existed but the target database had
never been successfully created (e.g. devshell exited mid-init in a prior run),
postgres-init skipped createdb and the subsequent psql connection failed with
'database "<db>" does not exist'.
Now on reuse path we probe pg_database and create the target DB if missing,
making postgres-init fully idempotent across stale-state recovery.
Adds postgres-init-reuse-missing-db test.
