StackEnv v0.1.0 — Command Center preview

First public StackEnv preview for Linux. Includes repository and subproject discovery, read-only Git status, Portly application visibility, private screenshot indexing, an embedded loopback dashboard, SQLite snapshots, origin authentication, systemd user-service generation, doctor checks, and shared-tunnel-safe Cloudflare ingress output. Skills synchronization and multi-machine coordination are planned as separate audited milestones.