Fix Ask Mantosh knowledge-document count drift in SYSTEM_STATE.md

Problem

docs/SYSTEM_STATE.md currently describes 18 public Ask Mantosh documents in the published inventory, but the Known limits section says 17 public knowledge documents are indexed.

The canonical production-state document should not contain conflicting inventory counts.

Scope

• Determine the actual indexed/public knowledge-document count.
• Update docs/SYSTEM_STATE.md so all references agree.
• Check whether an existing audit can verify this count automatically.
• If not, add a deterministic documentation/content audit so future count drift fails CI.

Acceptance criteria

• One authoritative count is used throughout docs/SYSTEM_STATE.md.
• The count matches the current public knowledge corpus.
• CI or an existing deterministic audit detects future drift where practical.
• npm run verify passes.

Start with docs/SYSTEM_STATE.md and determine the actual public knowledge-document count from the current corpus. Check the existing audits and the npm run verify entry point to see whether deterministic count validation already exists; update the document and add or extend an audit so the acceptance criteria and verification command pass.