docs(mediainfo): document snapshot v2 negotiation

[SuperMonster003]

Summary

• add the MediaInfo API source document
• document strict snapshot v1/v2 selection and capabilities discovery
• document the stable v2 file, engine, inform, and tracks envelope
• add HTML and JSON artifacts generated with this repository's existing 1.1.8-compatible generator

Narrow integration

The remote baseline predates the MediaInfo documentation module. This PR adds only the standalone MediaInfo Markdown, generated HTML, and generated JSON. It does not pull in the later 6.8 documentation overhaul, Pinyin pages, offline-search rewrite, or unrelated project metadata.

Coordination

• Plugin contract and implementation: feat: add opt-in snapshot v2 contract AutoJs6-Plugin-MediaInfo#3
• Host schema negotiation and Rhino/Node bridge: https://github.com/SuperMonster003/AutoJs6-Private/pull/4
• Node Runtime facade: feat(mediainfo): expose snapshot v2 negotiation AutoJs6-Plugin-NodeJs-Runtime#1
• API documentation: docs(mediainfo): document snapshot v2 negotiation #15
• TypeScript declarations: feat(mediainfo): declare snapshot v2 APIs AutoJs6-TypeScript-Declarations#8

All five pull requests remain Draft and should be reviewed as one coordinated contract set. None of them changes a release version or authorizes a merge/release.

Validation

• generated with the remote baseline's own generator and template
• JSON parses successfully
• all 156 relative HTML references resolve on the remote baseline
• v1 schema, v2 schema, capabilities, and defaultSnapshotSchema markers are present

Not included

• Info_Parameters
• unrelated documentation modules
• version bump or publication