Add new oidc category (2 endpoints)

[ldraney]

Parent Issue

#86 — Expand Octokit coverage

Category: oidc (NEW — no file exists yet)

File to create: src/tools/categories/oidc.ts

Methods to Add (2)

Method	Route
getOidcCustomSubTemplateForOrg	GET /orgs/{org}/actions/oidc/customization/sub
updateOidcCustomSubTemplateForOrg	PUT /orgs/{org}/actions/oidc/customization/sub

Setup Required

1. Create src/tools/categories/oidc.ts
2. Export oidcCategory from src/tools/categories/index.ts
3. Add to ALL_CATEGORIES in src/tools/generator.ts
4. Add to full and org-admin presets

Tool name format: github_oidc_<snake_case_method>.

Acceptance Criteria

• New file created with both methods
• Registered in generator.ts
• npm run build passes
• TOOLS.md updated