chore(cleanup): remove the June trials, orchestrator docs, dormant agent, caller-less code and the fix-round chain

R4-R7 of the cleanup list (decision 188): the June trial docs and
fixtures, the three orchestrator reference docs, the dormant
synthesis-agent, code with no caller (project-discovery, bash-normalize,
fidelity-diff, test-census, the next-session prompt validator, arm B and
the --workflow flag) and the fix-round chain. Living docs repointed; the
reasons for in-session orchestration and the all-opus pin are now written
in docs/architecture.md and docs/profiles.md.

New tests/lib/living-paths.test.mjs: living tracked text names only
plugin paths that exist (seen red with 22 dead pointers before this
commit). docs/T1-cc26-delegated-orchestration.md and
lib/review/gold-scorer.mjs stay until R-b: the frozen end-state registry
names them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/profiles.md

@@ -82,6 +82,14 @@ selected agents, overriding the session level:
 - **All other agents:** unset → inherits the session's effort level (a session
   that nothing sets runs at its model's default — `medium` on Opus 5.5).
 
+**Every agent is pinned `model: opus`.** The pin is set in each agent's
+frontmatter (operator decision, commit `40d8742`), because the profile
+resolver does not reach sub-agents: the profile picks the model for the
+phases, the frontmatter for the agents. The operator wants Opus on all Voyage
+work and accepted the roughly fivefold sub-agent cost against Sonnet. The
+glue, mechanical, retrieval and dormant roles were reconsidered for a Sonnet
+downgrade (operator, 2026-06-20) and kept on Opus: the pin stays firm.
+
 Native-effort precedence (harness): env `CLAUDE_CODE_EFFORT_LEVEL` > frontmatter
 `effort:` > session setting > model default, and a `maxEffortLevel` setting or
 an organization effort cap still limits the result. `MAX_THINKING_TOKENS=0` has