Add PreCompact hook for conversation archiving, remove /clear command

- Add PreCompact hook in agent-runner that archives conversations before
  compaction, using session summary from sessions-index.json for filename
- Remove /clear command (programmatic compaction not supported by SDK)
- Add /add-clear to RFS for future implementation
- Update CLAUDE.md templates with memory system instructions

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -56,11 +56,6 @@ Talk to your assistant with the trigger word (default: `@Andy`):
 @Andy every Monday at 8am, compile news on AI developments from Hacker News and TechCrunch and message me a briefing
 ```
 
-Clear conversation context:
-```
-/clear
-```
-
 From the main channel (your self-chat), you can manage groups and tasks:
 ```
 @Andy list all scheduled tasks across groups
@@ -104,6 +99,9 @@ Skills we'd love to see:
 **Platform Support**
 - `/setup-windows` - Windows via WSL2 + Docker
 
+**Session Management**
+- `/add-clear` - Add a `/clear` command that compacts the conversation (summarizes context while preserving critical information in the same session). Requires figuring out how to trigger compaction programmatically via the Claude Agent SDK.
+
 ## Requirements
 
 - macOS Tahoe (26) or later - runs great on Mac Mini