v0.1.19

Patch Changes

Dogfooding: rust-doctor scanned itself and three warnings got fixed.

• mcp: replace a diags[0] index with filter_map + .first()
• setup: replace an agents[i] index with filter_map + .get(i)
• setup: replace Box<dyn Error> with a typed SetupError enum, following the project error convention

Reliability dimension 99 -> 100.

Full Changelog: v0.1.18...v0.1.19