Write 'Common Errors' (evm/troubleshooting/common-errors)

**Page:** `evm/troubleshooting/common-errors.mdx`

**Scope:** Reference table of common error codes (`CONTRACT_REVERT_EXECUTED`, `INSUFFICIENT_GAS`, `INVALID_SOLIDITY_ADDRESS`, etc.) → cause → fix. Markdown table.

### Acceptance criteria
- [ ] Replace the placeholder template with real content
- [ ] Remove `hidden: true` from the frontmatter
- [ ] Follow the style guide: **markdown tables only** (no HTML ``), and avoid AI-tell phrasing (no em-dashes, "delve", "leverage", "not just X but Y")
- [ ] Add working cross-links to related pages
- [ ] Confirm any code samples run on testnet