Add os-select and os-toggle widget contracts with thin Playwright handlers

[danielbdyer]

Motivation

• Expand runtime widget coverage for high-frequency families (selects and toggles) by codifying domain contracts so capability derivation and resolution use typed semantics instead of ad hoc heuristics.
• Keep runtime handlers Playwright-specific and intentionally thin to avoid domain leakage while preserving stable execution receipts and degraded-locator signaling.
• Provide test coverage and authoring guidance so knowledge authors map affordances to contracts consistently.

Description

• Added two domain WidgetCapabilityContract entries: os-select and os-toggle, and registered them in the contract registry (lib/domain/widgets/contracts.ts).
• Implemented minimal Playwright-only handlers osSelectHandlers and osToggleHandlers (lib/runtime/widgets/os-select.ts, lib/runtime/widgets/os-toggle.ts) and wired them into the runtime handler registry (lib/runtime/widgets/index.ts).
• Updated discovery mapping so combobox/select inputs resolve to os-select and checkbox/radio/switch resolve to os-toggle, and aligned supported-action mappings (lib/domain/discovery.ts).
• Ensured engage/enter flows include structured metadata in execution receipts by returning locatorStrategy, locatorRung, and widgetContract for enter outcomes in addition to observed effects (lib/runtime/engage.ts).
• Added focused contract-first and runtime tests exercising affordances/preconditions, failure-mode stability, degraded locator rung semantics, select execution metadata, and toggle mutation behavior (tests/widget-contracts.spec.ts, updates to tests/runtime-errors.spec.ts).
• Updated authoring guidance to map common affordances to the new widget contracts and refreshed generated type projections so widget unions and supported-action maps include the new families (docs/authoring.md, regenerated lib/generated/tesseract-knowledge.*).

Testing

• Ran npm run types to regenerate types and projection artifacts and it completed successfully.
• Ran targeted tests npm test -- tests/widget-contracts.spec.ts tests/runtime-errors.spec.ts and observed all tests in that run passed (15 passed).
• Ran the full test suite with npm test and observed the suite complete successfully with the test summary showing 118 passed, 2 skipped.

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Codex Task