Add spell checking (typos or cspell) with CI integration

## Recommendation

### 📋 Add Automated Spell Checking

No spell checking configuration found (`.cspell.json`, `.typos.toml`, or similar). Typos in user-facing strings, documentation, and code comments go undetected.

## How to Fix

**Recommended: `typos`** (fast, Rust-based, low false-positive rate)
```bash
# Install
cargo install typos-cli
# Or use in CI
- uses: crate-ci/typos@master
```

Create `_typos.toml`:
```toml
[default.extend-identifiers]
# Add project-specific terms here

[files]
extend-exclude = ["pnpm-lock.yaml", "src/locales/**"]
```

---
**Category:** Quality | **Priority:** Nice-to-have | **Effort:** Small
Part of #11022
_Filed by repo-audit skill_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-11075-Add-spell-checking-typos-or-cspell-with-CI-integration-33e6d73d36508117ab84fd7f0c28ac8b) by [Unito](https://www.unito.io)