Add production source location plugins

[SweetRetry]

Summary

• resolve build-time data-agentation-id metadata before falling back to React internals
• add a separately publishable @agentation/source-locations workspace package with Next.js/Turbopack and Vite integrations
• generate compact manifests containing repository-relative paths and positions without source content
• preserve existing Turbopack rules while running instrumentation first
• cover .js, .jsx, and .tsx, and avoid instrumenting shadowed custom component bindings
• document single-project and monorepo setup

Testing

• pnpm test
• pnpm build
• pnpm install --offline --ignore-scripts --frozen-lockfile
• npm pack --dry-run --json in plugins/source-locations

Closes #198

[vercel]

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