refactor: share package version lookup

[adity982]

Summary

• move the duplicated package manifest version reader into @ayo-dev/core/node
• have both the CLI and MCP server pass their own import.meta.url
• preserve the safe 0.0.0 fallback without pulling Node-only code into the Worker export

Validation

• direct TypeScript build and typecheck passed for core, CLI, and MCP packages
• node packages/cli/dist/ayo.js --version -> 0.3.1
• shared helper resolves both CLI and MCP package versions to 0.3.1
• pnpm install --frozen-lockfile resolved dependencies but this runner's pnpm policy rejected unapproved third-party build scripts (esbuild, sharp, workerd)

Closes #61