boost v1.2.99

What's changed

Other changes

• fix(cli): seal BrokenPipeError, fix help-routing aliases, bump launcher floor to 3.12 (#814)
• fix(mcp): add --dry-run, fail on a named missing host, name a phantom unregister (#810)
• fix(test,lint): boost test's lint check now agrees with boost lint (#786)
• fix(pulse,who): a filter matching nothing no longer claims an empty journal (#780)
• fix(tap): local-path diagnosis, --at pre-clone validation, single/multi skip parity (#772)
• batch: train-17 — ten PRs in one release (#751 #772 #775 #780 #786 #789 #804 #805 #810 #814) (#827)