chore(ci): implement tiered GitHub Actions runner strategy

This commit optimizes CI/CD performance and reproducibility by migrating workflows from `ubuntu-latest` to a three-tier runner strategy using specific Ubuntu 24.04 images.

Specific changes include:
- **Lightweight Utility Jobs**: Migrated status checks, labelers, triage, changelog generation, and metadata tasks to `ubuntu-24.04-arm` to take advantage of shorter queue times for non-x86 dependent tasks.
- **Gradle & Heavy Jobs**: Pinned heavy workloads (Android builds, host checks, CodeQL, Dokka, publishing) to `ubuntu-24.04` to ensure build reproducibility and avoid unexpected breakages from `ubuntu-latest` alias updates.
- **Desktop Release Matrix**: Updated the desktop release strategy to include `ubuntu-24.04` and `ubuntu-24.04-arm` for cross-platform native packaging.
- **Documentation**: Updated `AGENTS.md`, `GEMINI.md`, and `.github/copilot-instructions.md` to document the new runner strategy and provide guidelines for future workflow modifications.

Workflows updated:
- `promote.yml`, `release.yml`, `pull-request.yml`, `merge-queue.yml`, `codeql.yml`, `docs.yml`, `reusable-check.yml`, and various utility/triage workflows.

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

.github/workflows/codeql.yml

@@ -28,7 +28,7 @@ jobs:
     #   - https://gh.io/supported-runners-and-hardware-resources
     #   - https://gh.io/using-larger-runners (GitHub.com only)
     # Consider using larger runners or machines with greater resources for possible analysis time improvements.
-    runs-on: ${{ (matrix.language == 'swift' && 'macos-latest') || 'ubuntu-latest' }}
+    runs-on: ${{ (matrix.language == 'swift' && 'macos-latest') || 'ubuntu-24.04' }}
     if: github.repository == 'meshtastic/Meshtastic-Android'
     permissions:
       # required for all workflows