fix(filter): accept runtime numeric values in filter_by

[georgegebbett]

Problem

Interpolating a runtime number into a filter fails to type-check:

const n: number = 1214009;
multisearchEntry({
  collection: "matters",
  q: "*",
  query_by: ["title"],
  filter_by: `humanReadableId:=${n}`, // Error: Unknown token: ${number}
});

The value humanReadableId:=1214009 is valid at runtime, but there's currently no way to pass a runtime numeric value into filter_by. The backtick escape that works for string fields (field:=`${value}`) doesn't help here — Typesense rejects a backtick-quoted number with "Numerical field has an invalid comparator". So the one form that type-checks is the one the engine refuses, and vice-versa.

Cause

When a number is interpolated, the value arrives as the template-literal type `${number}`. The tokenizer's char-split (T extends \${infer Head}${infer Tail}`) collapses the whole placeholder into Head, which doesn't extend NumericValue (Digit | "." | "-"), so it falls through to Unknown token: ${number}`. It's a coverage gap in the tokenizer.

Fix

Add a FilterTokenizer branch that treats a `${number}`/`${bigint}` placeholder as a NumToken and recurses on the tail. It's placed after the literal NumericValue branch, so literal digits still go through ReadNum and keep their exact value (NumToken<"20">). The tail recursion handles continuation clauses, arrays, and ranges:

• humanReadableId:=${n} -> valid
• humanReadableId:=${n} && title:foo -> valid
• humanReadableId:[${n}] and humanReadableId:[${a}..${b}] -> valid

Invalid filters are still rejected (wrong operator for a numeric field, unknown fields, etc.) — the fix isn't over-permissive.

Tests

Added tokenizer and ParseFilter cases for ${number}/${bigint} interpolation across :=, comparisons, arrays, ranges, and continuation clauses, plus a guard that literal numbers keep their exact NumToken value.

[tharropoulos]

Thank you for this!

[georgegebbett]

thanks for the merge! lmk when you are able to cut a release as would love to be able to upgrade to the version with the fix!