Adopt the Fleet code-health standard

[sarthakagrawal927]

Adopt the Fleet-wide measurable code-health contract in Chess Coach.

Acceptance criteria:

• expose one aggregate repository quality command
• cover formatting, lint, types, tests/coverage, unused code, complexity, duplication, dependency risk/cycles, suppressions, and repository hygiene
• run the gate in CI
• remove safe dead code before accepting any exception
• record every remaining numeric exception with an owner, rationale, issue, and review date in Fleet Workspace
• preserve Stockfish isolation/header constraints, evaluation perspective, routes, local-only AI coaching, and manual deployment boundaries

This issue is the independently shippable adoption unit.