feat(toc): support inherited noIndex

[kadymov]

Problem

noIndex can be set in page frontmatter and global configuration, but toc.yaml cannot consistently prohibit indexing for a page or a whole subtree. This also leaves TOC-only restrictions out of LLMS artifacts.

Changes

• expose boolean noIndex on TOC roots and items;
• propagate the effective value monotonically through sections and included TOCs, including a section's own href;
• preserve true when TOC metadata and frontmatter are merged in either order and loading mode;
• exclude affected pages from llms.txt and llms-full.txt using the resolved TOC, including worker builds;
• keep hidden independent: hidden pages remain absent from LLMS output but do not receive meta.noIndex;
• add unit and E2E coverage for roots, pages, sections, siblings, nested false, named and expanded includes, metadata conflicts, and --jobs.

Verification

• npm test — 1919 tests passed, 1 skipped;
• npm run typecheck;
• npm run lint — no errors;
• npm run build;
• npm run e2e — 214 tests passed, 1 skipped, 1 todo;
• focused LLMS E2E — 5 tests passed;
• git diff --check.

Schema: diplodoc-platform/ajv#64

Task: DOCSTOOLS-4902

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
98.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud