Add particle resources to the conversion-mismatch taxonomy

[Infiland]

Follow-up to #612 / PR #658 and #706 / PR #808.

Problem

The Resource Conversion Mismatch issue form was created before authored particle conversion shipped. Its description and resource-kind dropdown have no dedicated particle choice, forcing particle-system, type, and emitter problems into Other.

The Wiki's mismatch-report guidance also omits particles, so the two user-facing taxonomy surfaces no longer describe the converter's supported resource families accurately.

Acceptance criteria

• The issue-form description explicitly mentions particle resources.
• The resource-kind dropdown includes a dedicated Particle system, type, or emitter option.
• Diagnostics-and-Troubleshooting.md lists particle resources in its Resource Conversion Mismatch guidance.
• The Wiki wording and issue-form taxonomy remain consistent.
• A documentation-health regression test covers the particle option on both surfaces.
• No converter or generated-runtime behavior changes.