docs(rfc): propose harness-level goal-based loop

Introduce packages/loop as a capability seam covering goal-based (and
naturally proactive) loops around the existing agent-loop, deferring
time-based scheduling to a future dsh-schedule RFC. Four cordis service
seams — loop-as-session, pluggable Evaluator/Budget with EvaluatorSpec
tiers and protectedPaths, RoundHandoff, GoalReflector — plus a driver-
enforced Default-FAIL contract and reuse of packages/fs policy gate for
reward-hacking defense. Bilingual pair.

docs/rfc/INDEX.md

@@ -14,6 +14,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
 | [SQLite FTS5 session search](proposed/feature/2026-07-10-sqlite-session-query-provider.md) | 2026-07-10 |
 | [Stream workflow progress through tool calls](proposed/feature/2026-07-13-stream-workflow-progress-through-tool-calls.md) | 2026-07-13 |
 | [Developer-owned SDK projects](proposed/feature/2026-07-14-sdk-developer-projects.md) | 2026-07-14 |
+| [harness-level goal-based loop](proposed/feature/2026-07-16-harness-level-loop.md) | 2026-07-16 |
 
 ### Simplification