Restore contents:write permission for docs deploy (fix gh-pages 403)

[ChrisRackauckas-Claude]

Problem

The docs-deploy step fails: the documentation build passes, but deploydocs cannot push to gh-pages (403 / GITHUB_TOKEN is read-only).

Root cause

The CI-centralization migration to documentation.yml@v1 dropped the permissions: block from the Documentation.yml caller job. The reusable workflow (SciML/.github/.github/workflows/documentation.yml@v1) declares no permissions: of its own and deploys via GITHUB_TOKEN (Documenter auto-uses GITHUB_TOKEN when DOCUMENTER_KEY is absent). In a reusable-workflow call, the caller job's permissions flow through to the token. With no permissions: block on the caller, the token defaults to read-only and the gh-pages push 403s.

Fix

Add actions: write, contents: write, statuses: write to the build-and-deploy-docs caller job. contents: write is what lets deploydocs push to gh-pages. This mirrors the confirmed fix in OrdinaryDiffEqOperatorSplitting #90.

YAML-only change. Validated with python3 -c "import yaml; yaml.safe_load(...)". Full verification of the deploy requires a CI run on main (deploy only runs on push to main/tags, not on PR), so this cannot be verified end-to-end from the PR; the change is correct by matching the proven #90 pattern.

   build-and-deploy-docs:
     name: "Documentation"
+    permissions:
+      actions: write
+      contents: write
+      statuses: write
     uses: "SciML/.github/.github/workflows/documentation.yml@v1"
     secrets: "inherit"

Please ignore until reviewed by @ChrisRackauckas

[ChrisRackauckas-Claude]

Superseded by SciML/.github#102, which sets permissions: contents: write in the centralized documentation.yml reusable itself — so no per-repo permissions block is needed once v1 is retagged. Closing this in favor of the central fix.