* poteto-mode: add the Hillclimb playbook A generic, metric-agnostic scientific hill-climb loop. Fix a metric and a stop predicate, freeze a measurement harness, keep a decision.tsv, and loop one hypothesis at a time with before/after measurement, a regression gate, and one commit per accepted win. The agent supervises and delegates the attempts. Registered in the playbook list; perf-issue points here for sustained work. * setup-pstack: add the hillclimb model role The Hillclimb playbook reads a configured hillclimb model. Group it with bug-fix and perf-issue on the gpt-5.5-high-fast default so /setup-pstack offers the choice and the playbook reference is not dangling. * setup-pstack: split bug-fix, perf-issue, hillclimb into separate model lines * hillclimb: scope the autonomous-run deferral to the wake mechanism, not its stop rule * poteto-mode: drop the two-no-progress stop from Autonomous run; keep going past plateaus