Enforce MySQL string/text limits in SQLite

To ensure consistent column lengths, we'll add limits to string and text
columns which match MySQL defaults.

config/initializers/table_definition_column_limits.rb

@@ -0,0 +1,49 @@
+# Apply MySQL-compatible column limits when using SQLite.
+#
+# For string columns: defaults to 255 (MySQL's VARCHAR default)
+#
+# For text columns: converts MySQL's `size:` option to equivalent limits:
+#   - (blank/default): 65,535 (TEXT)
+#   - size: :tiny: 255 (TINYTEXT)
+#   - size: :medium: 16,777,215 (MEDIUMTEXT)
+#   - size: :long: 4,294,967,295 (LONGTEXT)
+
+module TableDefinitionColumnLimits
+  # Map MySQL size options to limits
+  TEXT_SIZE_TO_LIMIT = {
+    tiny: 255,             # TINYTEXT
+    medium: 16_777_215,    # MEDIUMTEXT
+    long: 4_294_967_295    # LONGTEXT
+  }.freeze
+
+  TEXT_DEFAULT_LIMIT = 65_535   # TEXT
+  STRING_DEFAULT_LIMIT = 255    # VARCHAR
+
+  def column(name, type, **options)
+    if type == :string
+      options[:limit] ||= STRING_DEFAULT_LIMIT
+    end
+
+    if type == :text
+      if options.key?(:size)
+        size = options.delete(:size)
+        options[:limit] = TEXT_SIZE_TO_LIMIT.fetch(size) do
+          raise ArgumentError, "Unknown text size: #{size.inspect}. Use :tiny, :medium, or :long"
+        end
+      elsif options.key?(:limit)
+        valid_limits = [TEXT_DEFAULT_LIMIT] + TEXT_SIZE_TO_LIMIT.values
+        unless valid_limits.include?(options[:limit])
+          raise ArgumentError, "Invalid limit #{options[:limit]} for text column. Use `size:` (:tiny, :medium, :long) or omit for default TEXT."
+        end
+      else
+        options[:limit] = TEXT_DEFAULT_LIMIT
+      end
+    end
+
+    super
+  end
+end
+
+ActiveSupport.on_load(:active_record) do
+  ActiveRecord::ConnectionAdapters::TableDefinition.prepend(TableDefinitionColumnLimits)
+end