fix: two findings from the agent-skill audit - #69

What

Two findings from Zack Asofsky's agent-skill-auditor, both verified before fixing.

1. localization ships code that contradicts its own guidance

SKILL.md prescribes:

Robust Mapping Strategy: When mapping existing UI text to keys, sort keys by string length (descending) and match longest strings first. This prevents short strings (like "NO") from matching parts of longer sentences.

resources/L10nBatchProcessor.cs iterated the mapping Dictionary in enumeration order with a bare Contains, and no sort.

It is worse than a missing optimization, because of the break:

foreach (var kvp in mapping)          // unspecified order
{
    if (!current.Contains(kvp.Key)) continue;
    ...
    matched = true;
    break;                            // first hit wins
}

A label reading "NO ITEMS FOUND" binds to a "NO" key and stops looking. It is also flagged matched, so it never appears in the unmatched list the method returns for exactly this purpose — a silent mis-binding rather than a visible failure. And since Dictionary enumeration order is unspecified, whether it happens at all varies between runs.

Fixed by sorting longest-first, once, outside the per-label loop.

2. physics-3d-collision's only reference file restated the spine

All 23 rows of references/troubleshooting.md's symptom table are already covered by SKILL.md — its eleven Fast-Path sections and twelve checklist steps — in different words. Spot-checked before removing:

The table is removed. The seven Unity Manual links in the file's Resources section are kept — they appear nowhere else, and linking documentation rather than restating it is the direction we want. SKILL.md's pointer is retitled from "Troubleshooting & Resources" to "Resources" to match.

Scope

One behavioral fix, one redundancy removal. No skill trigger or description changes.