Implement WebMCP authoring capabilities

[ErickWendel]

Summary

• expose all 15 authoring tools as editable, runnable showcase cards and use object-shaped inputs with a safe same-origin bridge fallback
• validate every WebMCP input against its schema before dispatch and split translation/description workflows into bounded focused capabilities
• translate deterministic grounded descriptions into the requested language, with truthful English fallback metadata when local translation fails
• publish exact revisions into a clean public browser context and include raw recording audio only after persisted consent from LocalStudio sharing UI
• cover every showcase card, operation progress, visual previews, exports, publishing, and public revision rendering

Verification

• npm run lint (0 errors; 1 pre-existing unused eslint-disable warning)
• npm run typecheck
• npm test (934 passed, 2 skipped tests; 1 skipped editor test file)
• npm run build:editor
• focused WebMCP/visual Playwright suite (5 passed)
• npm run test:e2e:coverage:webmcp (3 passed; 31.28% editor byte coverage for this focused scope)
• manual in-app browser validation: 15 discovered tools, 15 editable/sendable cards, create -> upsert -> inspect completed
• two-axis code review: no remaining P1/P2 standards or spec findings

Closes #173
Closes #174
Closes #175
Closes #176
Closes #177