chore: reconcile post-v0.11.1 mainline and modernize Actions

[eybersjp]

Purpose

Complete the repository cleanup after Development Modes (#53) and IDEA Authority Hardening (#54) landed.

Changes

• Reconcile README, ROADMAP, STRATEGY, memory and CHANGELOG with the actual repository state.
• Clearly distinguish published v0.11.1 from post-release functionality already integrated on main.
• Remove stale wording that described completed Issues Development Modes — reconcile onto v0.11.1 and complete increments 001–005 #50/IDEA authority hardening — port missing PR #35 protections to current architecture #51 as active work.
• Record Development Modes and IDEA Authority Hardening under [Unreleased].
• Modernize GitHub Actions using the current major versions already identified by repository dependency automation:
  • actions/checkout@v7
  • actions/setup-node@v7
  • actions/configure-pages@v6
  • actions/upload-pages-artifact@v5
  • actions/deploy-pages@v5
• Apply the action upgrades consistently across CI, release, maintainer-release and Pages workflows.

Verification

This is the final repository-reconciliation pass. Merge only after the full Ubuntu/Windows CI matrix and exact npm run release:validate command succeed.

No version bump, tag, GitHub Release or npm publication is performed by this PR.