feat: add yavy project create command

[vildanbina]

Summary

• Adds yavy project create command with interactive and flag-based modes
• Supports web crawl (--url) and GitHub repository (--github) sources
• Interactive prompts via @clack/prompts when required flags are missing
• Extends YavyApiClient with createProject() and ApiError class
• Adds error formatting with per-status-code user-friendly messages
• Full test coverage (197 tests passing)

Changes

• src/api/client.ts - Added ApiError, OrganizationInfo, ApiValidationError, mcp_url field, createProject() method
• src/commands/project/ - Command factory, payload builder, org resolver, types
• src/prompts/project-create.ts - Interactive flow with source type selection, URL/GitHub input, org selection
• src/utils/errors.ts - API error formatter mapping status codes to actionable messages
• src/utils/output.ts - formatProjectCreated() output formatter
• src/index.ts - Registered yavy project create under project parent command
• Docs: CLAUDE.md, docs/architecture.md, README.md updated

Test plan

• All 197 tests pass (pnpm test)
• Manual: yavy project create --url https://example.com --org my-org
• Manual: yavy project create --github owner/repo --org my-org
• Manual: yavy project create (interactive mode)