fix: cast "char" catalog columns to text in the schema fingerprint

First CI run of the drift check confirmed the whole upgrade path works -
baseline schema plus all twelve since-added migrations applied cleanly -
and then died inside the fingerprint itself:

    ERROR:  operator is not unique: text || "char"

WHAT IS "char" (WITH QUOTES)

Postgres catalog columns like pg_class.relkind, pg_attribute.attidentity,
and pg_default_acl.defaclobjtype use the internal single-byte type "char"
(quoted) - a different type from char(1). Concatenating text with "char"
is ambiguous: the parser finds more than one usable || operator via
implicit casts and refuses to guess. An explicit ::text cast picks one.

Only the "char" columns needed casts; booleans and reals concatenate fine
(anynonarray || text is unique for them).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>