chore(agents): inherit session model for judgment-tier subagents

Drop the pinned `model: sonnet` from the reasoning-heavy subagents so they
follow the session model instead of being forced down to Sonnet. Running an
Opus session now gets Opus subagents; deliberately dropping to a cheaper
session model is respected too.

Mechanical agents (browser-check, profiler, translator) keep their haiku pin
— that pin is a capability statement, not a stale default, and should hold
regardless of session model.

.claude/agents/code-quality.md

@@ -1,6 +1,5 @@
 ---
 name: code-quality
-model: sonnet
 description: Code quality specialist that runs build, lint, and type-check, then fixes any errors it finds. Use proactively after code changes to verify nothing is broken.
 ---
 

.claude/agents/plan-implementer.md

@@ -1,6 +1,5 @@
 ---
 name: plan-implementer
-model: sonnet
 description: Implements assigned tasks from a plan. Receives specific tasks from the parent agent, implements them sequentially, verifies with a build check, and reports back. The parent agent handles parallelization by spawning multiple plan-implementer subagents with different task subsets.
 ---
 

.claude/agents/react-doctor-fixer.md

@@ -1,6 +1,5 @@
 ---
 name: react-doctor-fixer
-model: sonnet
 description: Fixes React issues identified by react-doctor. Use when the parent agent has validated a react-doctor diagnostic and has a detailed fix plan. The parent agent provides the plan; this subagent implements the fix and re-runs react-doctor to verify.
 ---
 

.claude/agents/react-patterns-enforcer.md

@@ -1,6 +1,5 @@
 ---
 name: react-patterns-enforcer
-model: sonnet
 description: Reviews React code for anti-pattern violations specific to the 5chan project (useState/useEffect misuse, missing Zustand, copy-pasted logic) and fixes them. Use after writing or modifying React components, hooks, or state management code.
 ---