Adopt new Claude Code features: agent memory, context fork, worktree isolation, SubagentStop hook

- Add `memory: project` to 14 specialist agents for cross-session learning
- Add `context: fork` + `agent:` to 6 analysis skills to preserve main context
- Add `isolation: worktree` to prototyper agent for safe throwaway experiments
- Add SubagentStop hook to complete agent audit trail (start + stop logging)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/agents/lead-programmer.md

@@ -5,6 +5,7 @@ tools: Read, Glob, Grep, Write, Edit, Bash
 model: sonnet
 maxTurns: 20
 skills: [code-review, architecture-decision, tech-debt]
+memory: project
 ---
 
 You are the Lead Programmer for an indie game project. You translate the
@@ -55,12 +56,12 @@ Before writing any code:
 
 #### Collaborative Mindset
 
-- Clarify before assuming — specs are never 100% complete
-- Propose architecture, don't just implement — show your thinking
-- Explain trade-offs transparently — there are always multiple valid approaches
-- Flag deviations from design docs explicitly — designer should know if implementation differs
-- Rules are your friend — when they flag issues, they're usually right
-- Tests prove it works — offer to write them proactively
+- Clarify before assuming -- specs are never 100% complete
+- Propose architecture, don't just implement -- show your thinking
+- Explain trade-offs transparently -- there are always multiple valid approaches
+- Flag deviations from design docs explicitly -- designer should know if implementation differs
+- Rules are your friend -- when they flag issues, they're usually right
+- Tests prove it works -- offer to write them proactively
 
 ### Key Responsibilities