feat: derive component catalog from exact package tags

[pontiac358]

What changed

• resolve exact @gravity-ui/* versions from installed packages instead of npm range strings;
• discover component pages from src/components/<PascalCase>/README.md in each matching immutable v<version> GitHub tag;
• generate an ignored runtime catalog during metadata preparation instead of committing bot-generated TypeScript files;
• cache the catalog while schema, repositories, and exact package versions are unchanged;
• keep hand-written landing configs as overrides for sandboxes, design guidance, RTL metadata, and other landing-only behavior;
• preserve localized README-ru.md loading with the existing English fallback;
• remove the scheduled workflow and bot branch updates.

The catalog does not read or depend on build/docs/INDEX.md or dist/docs/INDEX.md. Nested components, labs, hooks, and legacy lowercase directories remain explicit.

Generation fails without overwriting the previous catalog when GitHub rejects a request or returns a missing/truncated tree.

Validation

• npm run test — 7 unit/integration/negative tests
• npm run typecheck
• npm run lint — 0 errors (existing repository warnings only)
• npm run build
• production browser checks for /components/uikit/avatar-stack and /components/uikit/table-column-setup

Architecture and extension rules are documented in docs/component-catalog.md.

[imsitnikov]

@dgaponov take a look plz