feat(#2584): Phase 3 — scheduler consumer + isolation adapters (#2635)

Final phase of #2584 (ADR-1239 Codex-binding amendment). execute-phase now negotiates dispatch.isolation and dispatches through the matching adapter, so a wave's independent plans run concurrently on six runtimes instead of one — with no runtime=== branch in the scheduler.

harness-worktree passes the host's declared isolation flag (claude, cursor); orchestrator-worktree creates the worktree via the Phase-2 verb and spawns the executor into it with the resolved argv/cwd (codex, opencode, kimi, kimi-code); none stays sequential. Undeclared/unknown/unresolvable isolation degrades to none — never an unisolated parallel run.

Fixes two shipped Phase-2 descriptors that per-host research found would fail at spawn: kimi lacked its headless flag (would launch the interactive TUI and hang the orchestrator), and kimi-code named a non-existent binary (Kimi Code installs as 'kimi'). Adds the worktree-path root confinement Phase 2 deferred here, and leading-dash guards on the resolver's prompt/cwd matching the existing git-argument guard.

Closes #2627

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/workflow-size-baseline.json

@@ -24,7 +24,7 @@
   "docs-update.md": 56494,
   "edit-phase.md": 12927,
   "eval-review.md": 10332,
-  "execute-phase.md": 93277,
+  "execute-phase.md": 93263,
   "execute-plan.md": 35143,
   "explore.md": 11127,
   "extract-learnings.md": 12893,