Potbot 0.5.0.dev7 - bounded artifact read Cogs

This source preview continues T01.3/G10 with three installed SYN Cogs: open an expiring artifact read lease, read an integrity-checked byte range, and close the lease while retaining the artifact. The optional 26-Cog profile preserves all prior profile identities and uses the existing inherited Embers, independent admission checks, artifact store and execution ledger.

Each admitted call records start, actual progress and completion/failure statistics. Reads return at most 8 KiB of raw data within the unchanged 16 KiB encoded-work limit. The local POSIX backend verifies the whole source using requests of at most 64 KiB; the controller checks lease expiry/revocation and host admission again after I/O. Migration 22 adds scoped, append-only leases/revocations without changing historical migrations.

All eight push/PR checks passed on the released feature tree. The real PostgreSQL fixture reconstructs the exact binary source after controller/service instance recreation within one test process, with reverse-order and duplicate delivery, eleven rejection cases, and REST/WebSocket monitoring. Retained source-bound evidence and a browser reconstruction viewer accompany the implementation.

Qualification is bounded reads on the existing local POSIX backend. Request sizes and logical verification counts do not measure physical disk traffic or peak process memory. Other backends, network transports, process crash recovery, resumable uploads and physical retention/GC remain separately unqualified. T01.3 remains in progress.

The release workflow builds an exact-tag wheel and source archive, checks a clean installation, and publishes checksums plus the source manifest. PyPI publishing remains disabled until its configured publisher is enabled; this preview does not change native custody or an installed runtime.

Implementation and limits: artifact-range Cog guide.