fix(data): fix removeColumn regex for unquoted column names

Make the trailing separator character class optional (`?`) so
removeColumn matches columns that are not quoted (e.g. `name text`
instead of `` `name` text ``). Without this, the regex required a
quote/separator char after the column name before matching whitespace,
which fails for unquoted DDL fields.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: cpcloud

internal/data/sqlite/ddlmod.go

@@ -339,7 +339,7 @@ func (d *ddl) removeColumn(name string) bool {
 	// Match column names that are quoted (backtick, single, double) or
 	// unquoted, followed by whitespace and the column type definition.
 	reg := regexp.MustCompile(
-		"^[`'\" ]?" + regexp.QuoteMeta(name) + "[`'\" ]\\s",
+		"^[`'\" ]?" + regexp.QuoteMeta(name) + "[`'\" ]?\\s",
 	)
 
 	for i := 0; i < len(d.fields); i++ {