feat: add opt-in snapshot v2 contract

[SuperMonster003]

Summary

• keep snapshot-v1 as the default while adding exact, opt-in snapshot-v2 negotiation through the existing Bundle
• adapt MediaInfoLib native JSON into a plugin-owned envelope with file/engine metadata, per-type track arrays, and isolated fields/attributes/extra extensions
• advertise supported schemas, default schema, and compact Info_Version through PluginInfo capabilities
• consume the shared mediainfo-api schema/capability contract instead of maintaining plugin-private wire constants
• complete the coordinated AutoJs6 host, Rhino, Node, documentation, and type-declaration integration while continuing to defer Info_Parameters

Compatibility boundary

• no AIDL method-signature change
• missing, null, or blank schema continues to return snapshot-v1
• explicit v2 requires an exact schema identifier and an exact plugin capability advertisement
• unknown, padded, or case-changed schema identifiers fail closed
• no version bump, merge, or Release in this PR

Validation

• plugin JVM tests and Android test compilation: passed
• QV710AF65F plugin contract/AIDL matrix: 5 tests passed
• QV710AF65F AutoJs6 Rhino/Node/real Android provider matrix: 5 tests passed
• QV710AF65F Node stable export/Promise conformance: 1 targeted test passed
• previous multi-track, multi-subtitle, MP4, WebM, FLAC + cover, malformed-file, minified Release, and large-file validation remains green
• Android lint and Debug/Release APK assembly for arm64-v8a, armeabi-v7a, x86, x86_64, and universal: passed
• packaged ELF/APK metadata verification: passed
• localized Markdown integrity: MARKDOWN_OK languages=10 artifacts=36

Coordinated pull requests

• Plugin contract and implementation: feat: add opt-in snapshot v2 contract #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 AutoJs6-Documentation#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.

Deferred work

Info_Parameters remains excluded from the discovery Bundle and is deferred to a dedicated on-demand API with explicit Binder payload-size tests. Direct get stream-number selection, stream counts, and InfoKind remain separate Roadmap items.