[TheGreatAxios]

Closes CL-9399

Summary

• LICENSE: the Interchange LGPL-2.1 text, byte-identical across @corbits repos (was the FSF text); add CLA.md and the cla.yml CLA Assistant workflow
• package.json: files ships README.md and LICENSE next to dist; add keywords; homepage points at #readme. Scripts: build is rm -rf dist && tsc -p tsconfig.build.json && bun run build:css (drops clean and build:js), test runs bun test src --pass-with-no-tests, test:e2e runs e2e, and a new check runs typecheck, lint, format check and unit tests. build:css, dep-guard, contrast-test, stories and stories:build stay because the build, CI and workbench use them. exports, sideEffects and packageManager are unchanged. Key order is oxfmt's
• tsconfig.json follows the standard template plus jsx: react-jsx, the DOM libs and the stories/Ladle includes. It adds exactOptionalPropertyTypes, noImplicitOverride, verbatimModuleSyntax, moduleDetection and resolveJsonModule, moves target to ESNext, and drops noUnusedLocals/noUnusedParameters (oxlint's no-unused-vars covers them). tsconfig.build.json follows the template (NodeNext, no source or declaration maps) and also excludes *.test.tsx
• exactOptionalPropertyTypes fixes (no behavior change): optional props and hook options that callers forward as-is accept undefined (ReasoningBlock.durationLabel, ChartFrame.className, MessageBubble.now/onRetry, AgentTurn.now, ArtifactNotice.pending, DialogContent.side, ProviderMark.className, SidebarItemRow.leaving, the parts-renderer reasoning and file parts, useControllableState value/onChange, useDismissablePopover open/onOpenChange); InfoTooltip passes defaultOpen ?? false to Radix
• .gitignore: the standard list plus build/ (Ladle's stories:build output); drops scratch/, .worktrees/, .agent-state/
• ci.yml: runs on all pull requests (was main-targeted only); bun run check, bun run build, contrast-test, dep-guard, bun run test:e2e (the exports check against dist), then a pack-and-import smoke under Node 24 that checks Button, ChatThread and Badge; drops the single-entry matrix and the explicit bun-version (packageManager pins it)
• CONTRIBUTING.md: 199 lines down to the standard template plus a CLA line, the e2e and CI gate paragraph, and a short Theme and stories section
• AGENTS.md (new): purpose, layout and the component rules that were in CONTRIBUTING (barrel and exports, dep-guard, "use client", peers, accessibility, naming)
• Delete PRODUCT.md, ARCHITECTURE.md, IMPLEMENTATION.md and SECURITY.md
• README: rename "Usage" to "Reference"

Stacked on #78.

• CONTRIBUTING gets a Releasing section: releases are manual, as in Interchange (npm version, push tags, gh release create --generate-notes, npm publish).
• CHANGELOG.md removed; GitHub Releases track changes. The README changelog link goes with it.

Commits

1. refactor: accept undefined on optional props for exactOptionalPropertyTypes
2. chore: use the Interchange LICENSE text and add the CLA
3. build: align package.json and tsconfig with the package standard
4. ci: run check and a Node pack smoke
5. docs: trim CONTRIBUTING, add AGENTS.md, drop planning docs

Checks

bun run check (268 unit tests), bun run build, contrast-test, dep-guard and bun run test:e2e pass; npm pack --dry-run lists 255 files including README.md and LICENSE; the Node pack smoke passes locally.