Prepare Tracebag 0.1.1 usability release

[poodlelab]

Summary

• make environment-scoped discovery and persisted-log opt-in explicit in the release setup
• download only the selected .NET diagnostic runner on first use
• add System-page scope guidance, API/CSRF documentation, and a copy-ready .NET target
• update the product site and version all release surfaces to 0.1.1

Verification

• ./scripts/verify.sh
• real Docker process discovery with an immutable GHCR runner tag absent locally before the request
• desktop and 390px mobile product-page render checks

AI assistance

Implemented and reviewed with Codex under the repository AI usage policy. The maintainer retains release responsibility.