fix(db): include f_unaccent function in schema.rb for test DB setup (#263)

The f_unaccent SQL function created by the internal chat migration is
not natively captured by schema.rb, causing db:test:prepare to fail
when creating indices that depend on it. Add the function definition
to schema.rb and extend SchemaDumper to preserve it across future dumps.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/initializers/schema_dumper_functions.rb

@@ -0,0 +1,27 @@
+# Extends the Rails schema dumper to include custom SQL functions that are
+# required by indices but not natively supported by schema.rb format.
+#
+# Without this, db:schema:load (used by db:test:prepare) fails because
+# schema.rb references indices that depend on f_unaccent() but the function
+# definition is lost during the dump (schema.rb only captures tables,
+# indices, and extensions, not custom functions).
+module SchemaDumperFunctions
+  private
+
+  def extensions(stream)
+    super
+    dump_custom_functions(stream)
+  end
+
+  def dump_custom_functions(stream)
+    stream.puts
+    stream.puts '  # Custom SQL functions (required before index creation)'
+    stream.puts '  execute <<~SQL'
+    stream.puts '    CREATE OR REPLACE FUNCTION f_unaccent(text)'
+    stream.puts '      RETURNS text LANGUAGE sql IMMUTABLE PARALLEL SAFE STRICT'
+    stream.puts "      AS $func$ SELECT public.unaccent('public.unaccent', $1) $func$"
+    stream.puts '  SQL'
+  end
+end
+
+ActiveRecord::SchemaDumper.prepend(SchemaDumperFunctions)

db/schema.rb

@@ -19,6 +19,13 @@ ActiveRecord::Schema[7.1].define(version: 2026_04_10_170003) do
   enable_extension "unaccent"
   enable_extension "vector"
 
+  # Custom SQL functions (required before index creation)
+  execute <<~SQL
+    CREATE OR REPLACE FUNCTION f_unaccent(text)
+      RETURNS text LANGUAGE sql IMMUTABLE PARALLEL SAFE STRICT
+      AS $func$ SELECT public.unaccent('public.unaccent', $1) $func$
+  SQL
+
   create_table "access_tokens", force: :cascade do |t|
     t.string "owner_type"
     t.bigint "owner_id"