feat: add provider-general Windows container distribution

[damiandelmas]

Summary

• add a provider-general Docker Desktop/WSL2 distribution for the complete Flex wheel
• add disposable module initializers, one persistent worker, durable volume storage, and universal stdio MCP
• add native PowerShell install/verify scripts with narrow source mounts
• add protected GHCR publication with exact tested-wheel reuse
• release as Flex 0.55.0

Validation

• 8 runtime-ownership tests passed
• 39 provider-general container checks passed (Codex, Claude Code, Goose, external module, live JSONL/SQLite, MCP, restart, recreation, persistence)
• native Windows PowerShell render passed
• native Windows real-source proof passed for Codex and Claude Code
• native live JSONL marker, MCP handshake, worker restart, Compose recreation, and volume retention passed

Release gate

GHCR publication remains gated until the final Docker Desktop restart/reboot persistence receipt is attached.