db e2e, tsconfig unification, eslint unification (#712)

- **add db e2e test package**
- **add assistant scratch directory**
- **add base tsconfig**
- **update exports definitions for library packages**
- **update `express` pkg to shared config...**
- **move e2e-db to shared tsconfig, add credentials...**
- **add deprecation note on client readme**
- **init eslint standardization**
- **remove ts roadmap**
- **tweak eslint config setups**
- **eslint**

Author: NiloCK

CLAUDE.md

@@ -3,13 +3,20 @@
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
 ## Commands
-- Build: `yarn build`
+- Build: `yarn build` (builds all packages in dependency order)
 - Dev: `yarn dev` (starts CouchDB, platform-ui, express)
 - Lint: `yarn workspace @vue-skuilder/platform-ui lint` or `yarn workspace @vue-skuilder/express lint:fix`
 - Type check: `yarn workspace @vue-skuilder/express type-check`
 - Unit tests: `yarn workspace @vue-skuilder/platform-ui test:unit`
 - Run single test: `yarn workspace @vue-skuilder/platform-ui test:unit <test-file-path>`
 - E2E tests: `yarn workspace @vue-skuilder/platform-ui test:e2e`
+- Database E2E tests: `yarn workspace @vue-skuilder/e2e-db test`
+
+### Backend Package Commands
+- Build common: `yarn workspace @vue-skuilder/common build`
+- Build db: `yarn workspace @vue-skuilder/db build`
+- Build express: `yarn workspace @vue-skuilder/express build`
+- Test e2e-db: `yarn workspace @vue-skuilder/e2e-db test`
 
 ## Style Guidelines
 - Use TypeScript with strict typing
@@ -21,4 +28,23 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 - Use async/await for promises
 - Error handling: try/catch blocks for async code
 - Use ESLint and Prettier for code formatting
-- Follow Vue 3 Composition API patterns
+- Follow Vue 3 Composition API patterns
+
+## TypeScript Configuration (Backend Packages)
+Backend packages (`common`, `db`, `express`, `e2e-db`) follow standardized TypeScript configuration:
+
+### Shared Base Configuration
+- **Target**: ES2022 with strict settings enabled
+- **Module System**: NodeNext for libraries, CommonJS for testing
+- **Base Config**: All backend packages extend `tsconfig.base.json`
+
+### Package-Specific Patterns
+- **Shared Libraries** (`common`, `db`): Dual CommonJS/ESM exports for maximum compatibility
+- **Node.js Services** (`express`): ES modules with NodeNext resolution
+- **Testing Packages** (`e2e-db`): CommonJS with Jest compatibility
+
+### TypeScript Best Practices
+- All backend packages use consistent ES2022 target
+- Strict type checking enabled (noUnusedLocals, noUnusedParameters, etc.)
+- ESM imports use `.mjs` extensions in build outputs
+- CommonJS exports available for Jest testing compatibility