Six tasks: (1) aura-core Ctx::now(); (2) thread the Ctx::new signature
change through aura-std's five test call sites; (3) aura-engine
production shrink (remove observe, run -> (), thread the run-loop Ctx);
(4) migrate the engine test suite to a test-local Recorder fixture +
drained channel (the finish-threading task — the test module is one
compile unit, so it restores the full cargo test); (5) eight new
node-recording proof tests; (6) ledger C8/C22 realization notes + the
ship gate (workspace test, clippy, purity grep).
Recon found the spec undercounts Ctx::new call sites (9, not 3): the
aura-std and aura-engine run-loop sites also break on the signature
change and are threaded in tasks 2-3.
refs #2
