[Electric 2.0] Cleanup Out-of-Date Examples

## Goal
Remove or update examples that don't align with 2.0 story

## Scope
- Audit `/examples/` directory (20+ examples)
- Archive 1.0-style patterns that are superseded
- Update key examples to use TanStack DB
- Ensure all examples show "works with your stack" philosophy

## Dependencies
New patterns documented

## Acceptance Criteria
All public examples reflect 2.0 best practices

## Context
Part of Electric 2.0 launch. Examples are critical for developer adoption - they need to showcase the best patterns.