docs(ttxdb): scope positional input dedup to NewInput-built inputs

Signed-off-by: Evan <evanyan@sign.global>

Author: EvanYan1024

docs/services/storage/ttxdb.md

@@ -102,4 +102,6 @@ way, one row per member carrying the token's full quantity; sent-amount
 aggregation counts each `(token ID, enrollment ID)` pair once
 (`InputStream.UniquePerInput`), falling back to
 `(action index, input index, enrollment ID)` when the token ID has been
-filtered out of the metadata.
+filtered out of the metadata. Positional deduplication applies only to inputs
+built through `token.NewInput`, which marks the position as known; a
+literal-built input without a token ID keeps the previous keep-all behavior.