Simplify TypeScript declarations: use manual .d.mts with rollup copy plugin

Co-authored-by: hzhangxyz <[email protected]>

Author: Copilot

bnf/atsds_bnf/.gitignore

@@ -1,3 +1,3 @@
 *
 !index.mjs
-!index.mts
+!index.d.mts

bnf/atsds_bnf/index.d.mts

@@ -0,0 +1,13 @@
+/**
+ * Parse Dsp format (human-readable) to Ds format (internal S-expression)
+ * @param input - The Dsp format string to parse
+ * @returns The Ds format string
+ */
+export function parse(input: string): string;
+
+/**
+ * Unparse Ds format (internal S-expression) to Dsp format (human-readable)
+ * @param input - The Ds format string to unparse
+ * @returns The Dsp format string
+ */
+export function unparse(input: string): string;