fix(agents): no agent is pinned below the high floor

Operator rule (2026-10-05): standard is Opus 5.5 at reasoning effort High. Four retrieval agents (architecture-mapper, dependency-tracer, git-historian, task-finder) pinned effort: medium in frontmatter, which overrides the session level, so every /trekplan exploration ran part of its swarm below the floor. They came from fdd3ad8 on the premise that unpinned agents inherit high; e4e37f9 corrected that (unpinned inherits the session; Opus 5.5 defaults to medium), so the reason for medium was already gone. All four now pin high; the other agents keep following the session (operator's choice). docs/profiles.md (one bullet for the eight pinned agents), CLAUDE.md and README.md updated; the model-default sentence stays. Dated decision records and CHANGELOG untouched.

Red: 4 of 5 new tests fail on the pre-fix files - effort floor over all agents (offenders: the four), the four pin exactly high, no live doc says retrieval runs at medium (hits docs/profiles.md:76, CLAUDE.md:85, README.md:806), profiles.md names the four as high. Known-positive control green on arrival.
Verify 153/153 (agent-frontmatter, doc-consistency). SC9 probe: npm test green under a scratch HOME with CLAUDE_PLUGIN_DATA empty, nothing under its plugin data dir. Suite 1393 (1391/0/2).

The change is repo-true, not installed-true, until a release.

Voyage order 20261005T104513Z-1250514346, plan step 5/5.

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

agents/architecture-mapper.md

@@ -4,7 +4,7 @@ description: |
   Use this agent when you need deep architecture analysis of a codebase — structure,
   tech stack, patterns, anti-patterns, and key abstractions.
 model: opus
-effort: medium
+effort: high
 color: cyan
 tools: ["Read", "Glob", "Grep", "Bash"]
 ---

agents/dependency-tracer.md

@@ -4,7 +4,7 @@ description: |
   Use this agent when you need to trace import chains, map data flow, or understand
   how modules connect and what side effects they produce.
 model: opus
-effort: medium
+effort: high
 color: blue
 tools: ["Read", "Glob", "Grep", "Bash"]
 ---

agents/git-historian.md

@@ -4,7 +4,7 @@ description: |
   Use this agent to analyze git history for planning context — recent changes,
   code ownership, hot files, and active branches relevant to the task.
 model: opus
-effort: medium
+effort: high
 color: yellow
 tools: ["Bash", "Read", "Glob", "Grep"]
 ---

agents/task-finder.md

@@ -5,7 +5,7 @@ description: |
   related to the planning task. Replaces generic Explore agents with targeted,
   structured code discovery.
 model: opus
-effort: medium
+effort: high
 color: green
 tools: ["Read", "Glob", "Grep", "Bash"]
 ---