A group-owned personal DID is now working end to end against a real
inbound call: it rings every authorized group member simultaneously, first
to answer wins, and members whose own tier/allowed_numbers don't authorize
the caller are correctly skipped.
Updates the code comments that were written before that confirmation
existed (the Busy(15) block's "NOT yet confirmed live", and the group-ring
script's unverified-SHELL() note), and documents all four fixes plus the
"Commit Changes" caveat in the Anveo setup guide's bugs-fixed section so
the next person hitting one-ring-then-busy has the trail.
Also clears the guide's "Still open" section: the 2-number account cap no
longer applies, and the interactive walkthrough it described as unbuilt
was built (_pstn_anveo_walkthrough).