Codag SDK v0.2.0

Codag SDK v0.2.0 adds the coding-agent cost API across Python, TypeScript, and Go.\n\n- Action-aware tool-result reduction via POST /v1/actions/reduce\n- Contentless tool-usage metrics and savings analytics\n- Usage, pricing, reliability, trial-report, and workspace-policy clients\n- Conservative fail-open response handling and typed error mapping\n- Updated OpenAPI contract, privacy boundary, package checks, and live production suites\n\nVerified with 240 unit/contract tests, downstream package installs, and 21 live production checks.