docs: sync prerelease contracts across repositories

[kovawx]

Summary

Synchronize docs/develop with the current pre-release source lines:

• core/develop at b356dc8f728cbd3d476a7441877f1b2dd5d708cb
• zboard/develop at debfa56174fdc3711a042413e7c239ff65e5f134
• znet-sink/main at bfaf063de33e59e77c19a9c447f28f023e5f4b5f

Changes

• document VLESS REALITY + standard Xray Vision flow boundaries and verified combinations
• define Zboard single-subscription access isolation, canonical encoded Zero delivery, strict client User-Agent handling, and managed ZRS publication/persistence
• align ZNet-Sink subscription format detection and User-Agent override semantics
• document event-first live connections, bounded local history, raw IPC diagnostics, effective URLTest probes, and Windows flag rendering
• clarify that Windows system proxy does not provide TUN-level UDP/WebRTC/DNS interception

Validation

• verified all added JSON examples parse successfully
• verified Markdown code fences are balanced
• reviewed the final branch diff: 6 documentation files, 1 commit, no navigation or project metadata changes
• repository CI remains the authoritative VitePress/link validation because the execution environment could not resolve GitHub for a local dependency install