Supertamer dev-20260904c (build 29) — Account-global short references

#T12 now names the same task on every Mac signed into the same iCloud account.

Short references used to be numbered per device, so a reference handed to an agent on the other Mac resolved to a different row — or to nothing. The number now comes from a ledger in the iCloud account's private database, issued once and never reused (A-093).

Raise both Macs to this build at the same time. The first sync pass after launch migrates this Mac's existing numbers into the ledger: numbers that do not collide are kept exactly as they were, and only the loser of a collision is renumbered. A Mac left on an older build isolates the new ledger rows and keeps syncing everything else; it recovers by refetching the zone once it is raised.

Old bare references to a renumbered entity may point at a different entity. No aliases or redirects are kept — canonical supertamer:// addresses are unchanged.

What is in it:

• The account ledger, with one number per entity and one entity per number enforced in storage (migration v68)
• A conditional atomic allocator: counter, assignment and claim confirmed in a single all-or-nothing CloudKit save, so a failed attempt leaves nothing behind
• Automatic migration of each Mac's existing numbers, with no confirmation step and nothing to clean up afterwards
• Issuance on every sync pass, so an entity created offline is saved immediately without a number and is numbered when the connection returns
• A row with no number yet shows no chip and offers no Copy Reference rather than a placeholder

Source commit: c588220c21856dda5cde760dfc3d3a0eb8d8bb1d
zip SHA-256: cbe3e11a90aae0b7e59dbb936f38fcc055cfbb50b43a83f0216f5b05953bdfd3