feat(gitea): add-host-runner.sh for multi-runner CI parallelism
- scripts/gitea/add-host-runner.sh: stand up Nth independent host-mode runner
as its own launchd service (separate config/.runner/workdir, shared
runner.env token, admin-API registration token, idempotent reload)
- GITEA_VM_SETUP.md 11.5: document multi-runner setup, fleet list/prune,
and removal; 3 runners x capacity 2 ~= 6 parallel slots (verified)
Live fleet: learning-ai-mac (brew) + 2 added runners, all online; stale
offline registrations pruned.
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