Create provisioning scripts for self-hosted CI runners

[ny4i]

Problem

Self-hosted CI runners (Linux, Windows, macOS) are manually provisioned. If a runner VM dies or needs re-provisioning, someone has to manually install Qt, Hamlib, CMake, system dependencies, etc. by following docs in ~/.claude/SELF_HOSTED_RUNNERS.md.

This just bit us: the Linux runner was missing libpulse-dev (required by Qt6Multimedia), causing link failures. The fix was manual apt-get install via SSH.

Proposal

Create provisioning scripts for each runner platform:

• scripts/ci/setup-linux-runner.sh — installs Qt (via aqtinstall), Hamlib, system deps (libpulse-dev, libasound2-dev, libgl1-mesa-dev), linuxdeploy, registers GitHub Actions runner
• scripts/ci/setup-windows-runner.ps1 — installs Qt, MinGW, Hamlib, NSIS, 7-Zip, Git, Defender exclusions, registers runner
• scripts/ci/setup-macos-runner.sh — installs Homebrew, Qt, Hamlib, create-dmg, code signing cert import, registers runner

Scripts should be idempotent (safe to re-run) and version-pinned to match build.yml env vars (QT_VERSION, HAMLIB_VERSION).

Acceptance Criteria

• Linux provisioning script that produces a working runner from a clean Ubuntu 24.04 install
• Scripts read version numbers from build.yml or a shared config (single source of truth)
• Idempotent — re-running skips already-installed components
• Windows and macOS scripts (lower priority, can be follow-up)

Context

• Current runner docs: ~/.claude/SELF_HOSTED_RUNNERS.md
• Runner details: ~/.claude/projects/.../memory/ci-runners.md
• Related fix: commit 563ce39 (added libpulse-dev install step to build.yml as safety net)