Fix deep scan results dropped after wildcard or multi index tokens

[fudianchn]

AI disclosure: this change was prepared with AI coding agents, reviewed and revised line by line by me.

What

$..*.title returns the four book titles again. $..[0,2].author returns authors 0 and 2. $..[2].author still returns only author 2. A wildcard fed by a deep scan used to drop every result, so $..*.* returned 13 instead of 31 elements.

Why

Since 2.7.0 a deep scan over an array dropped every leaf result behind a wildcard or multi index token, returning an empty list.

How

New method acceptsUpstreamArrayIndex replaces the string comparison in the leaf filter. Only ArrayIndexToken restricts, by its real indexes. Wildcard, slice, scan, property and predicate tokens accept every element. A token without a previous link is mounted by a function parameter evaluation (see Length), so it accepts every element instead of dereferencing the missing link.

Root cause

PR #715 added a filter that compares the path fragment of the token before the leaf with the fed array index. "[*]" never equals "[0]", and "[0,2]" never equals either, so the results were dropped.

Testing

• DeepScanTest: $..*.title and $..[0,2].author fail on main and pass with the fix; the $..[2].author guard (issue Unexpected result when executing a jsonpath on json array #273) passes on both.
• Function parameter family: $..*.length() threw NullPointerException in the first version of this fix and now returns 31 like the completed scan results; $..[0].length() and $..[*].length() return 18 and 31.
• Snapshots: $..*.* returns 31, $..[1:3].author accepts all four authors, $..[-1].author stays empty (pre-existing negative index gap).
• Module suite: 937 tests pass, ./gradlew build green.

Not covered:

• Deep scan plus slice accepts every element instead of the exact [from,to) range; exact filtering needs the array length at the leaf, left out.
• Negative indexes before the leaf never match; multi property leaves do not filter. Both pre-existing.

Verification of the original issue

JsonPath.read(json, "$..*.title") on the books example: [] on 2.7.0 and main, the four titles with this fix.

Fixes #1052