v3.7.0

• feat: Multiple accounts per cloud provider, no juggling.
• feat: Add a second AWS, DigitalOcean or any cloud account in the providers list. Press a on the row, give both configs a label and they live side by side. Existing hosts stay yours.
• feat: Each labeled config syncs in its own lane. Markers carry the label, so two accounts never claim each other's hosts and a --remove on one doesn't touch the other.
• feat: Vault SSH role and address resolve per labeled config, so work and personal can sign with their own roles in their own Vaults.
• feat: purple sync digitalocean:work targets one config; the bare provider name still syncs all configs of that provider.
• feat: purple add --label work and purple provider remove digitalocean:work round out the CLI.
• change: Faster Nix release builds. CI's nix flake check now whitelists the source files it needs and skips LTO, saving ~20 minutes per release.
• change: ~/.purple/sync_history.tsv first column now reads provider[:label] (e.g. digitalocean:work) for labeled configs. Bare configs keep the plain provider name. Scripts grepping the file may need updating.
• Thanks to @AndreyOkh for suggesting multi-account support.