or.2: orchestrator-agent design correction — no nested subagent dispatch

Claude Code categorically forbids subagents from spawning other
subagents (code.claude.com/docs/en/sub-agents and the Agent SDK
subagents page). The `or.1` architecture (and `pr.1` that ran on
top of it) presumed a named-exception for `ailang-implement-
orchestrator` to dispatch implementer / spec-reviewer / quality-
reviewer / tester per task. That exception never existed at the
platform level; the `Agent` tool was silently dropped from the
orchestrator-agent's tool set at dispatch time.

Architecture revised, doc-only:

- Per-task phases (implementer → spec-compliance check → quality
  check) now run as sequential role-switches in the orchestrator-
  agent's own context, not as nested subagents.
- The four role-files (implementer / spec-reviewer / quality-
  reviewer / tester) become phase reference files the
  orchestrator-agent consults at role-switch boundaries.
- Boss-context offload preserved; fresh-per-phase context given
  up (the property that drove or.1's nested-dispatch design is
  not buildable in Claude Code).

Files touched:
- skills/implement/agents/ailang-implement-orchestrator.md
  (frontmatter, Iron Law, Phase 2/3 rewrite, rationalisations,
  red flags)
- skills/implement/SKILL.md (frontmatter, Iron Law, sub-status
  vocabulary note, cross-references)
- skills/README.md (Conventions: no more named exception; agent
  roster: role-files recast as phase references)
- docs/journals/INDEX.md (or.2 entry appended)
- docs/journals/2026-05-11-iter-or.2.md (new — full rationale)
- docs/roadmap.md (P1 tool-wiring item removed; resolved as
  categorically-not-fixable)
- docs/WhatsNew.md (user-facing correction entry appended)

No code changes; no bench impact; CLAUDE.md untouched (no stale
references to fix there).

docs/roadmap.md

@@ -41,22 +41,6 @@ context. Pick the next milestone from P1.)_
 
 ## P1 — Next
 
-- [ ] **\[todo\]** `Agent` tool wiring for the dispatched
-  orchestrator-agent — `skills/implement/agents/ailang-implement-orchestrator.md`
-  declares `tools: Read, Edit, Write, Bash, Glob, Grep, Agent`, but
-  the first real dispatch (pr.1) reported `Agent` was not in its
-  actual tool set, forcing degraded-mode execution (per-task
-  sub-loop did not run; all tasks executed inline in the
-  orchestrator's own context). Diagnosis needed before fix-scope
-  can be set: Claude Code restriction on nested-subagent dispatch?
-  Frontmatter parsing detail? Deferred-tool issue at the harness
-  layer? This blocks the or.1 design goal (Boss-context offload via
-  fresh-subagent-per-task isolation); Boss-context offload itself
-  still works because per-task detail collapses into one
-  end-report regardless.
-  - context: `docs/journals/2026-05-11-iter-pr.1.md` Boss-side
-    addendum + Audit close section.
-
 - [ ] **\[milestone\]** Post-22 Prelude — ship `Show` / `Eq` / `Ord`
   with the three total-orderable primitive instances (Int, Bool, Str);
   rewire `print` through `Show.show`. Float gets `Show` but **not**