fix(assistant): require complete factual advice answers

[lweberru]

Release blocker

The first release of #109, run 38965899217, correctly failed qualification: 112/114 cases passed. governance-folders-advice and devops-git-advice returned introductory explanations without the required actual facts. The continuous dialogue passed 13/13. Build and deploy were skipped. The failed receipts are retained; this is not a rerun of that source.

Focused correction

• Reinforce the complete factual explanation contract at the end of trusted general-advice system context. Provenance and follow-up decisions must not replace an actual answer; requested native defaults, null semantics, limits and exclusions belong in explanation.
• Preserve the separate bounded firewall-requirements dialogue, all source/scope/validation safeguards and explicit acceptance/execution boundaries.
• Verify delivery for every affected advice topic and preserve the user message.
• Regenerate source-bound knowledge and scenario inventory using existing generators. No factual oracle, scenario expectation, execution capability, model or validation threshold was weakened.

Evidence

• npm run check: passed; 809 unit tests passed, 66 environment-dependent skipped, static generated freshness, lint, types and build green.
• Real configured model, dedicated in-memory local test token, execution disabled: governance-folders-advice 2/2; devops-git-advice 2/2. Knowledge hash 5db344a9009f2d3e3a519ac6dbef9f4f614611101866756d4e2ad6f142667a67; factual suite hash unchanged bba638db669752c98b826684f0456cead383c02d249aad1899e56b565d3632a4.
• Complete repeated real-model suite and continuous journey remain mandatory on the exact merged source through the normal manual release workflow before activation.
• No customer Apply or production deployment.