Lint: Require `name` key in each `toc.yaml` entry

**Description:**
Each entry in `toc.yaml` must include a `name` key.

**Current behavior:**
Entries without a `name` key are accepted without errors.

**Expected behavior:**
Linting or validation should fail if an entry is missing the `name` key.

**Steps to reproduce:**
1. Add an entry to `toc.yaml` without a `name` key
2. Run linting or validation

**Acceptance criteria:**
- Linting fails if any `toc.yaml` entry does not have the `name` key
- Error message clearly indicates the missing `name` key and entry location