docs: fix hook names and prompt tags in documentation

- Fix outdated hook names: prompt:before → experimental.chat.system.transform
- Fix outdated hook names: tool.execute.before → (removed, file tracking is in tool.execute.after)
- Fix outdated hook names: compaction:before → experimental.session.compacting
- Add missing event hook documentation
- Fix README example to show correct <hot_session_state> tag instead of <workspace_memory_candidates>

AGENTS.md

@@ -261,24 +261,26 @@ export default {
 
 ## Plugin Hooks
 
-### `prompt:before`
+### `experimental.chat.system.transform`
 
 Injects workspace memory and hot session state into system prompt.
 
-### `tool.execute.before`
-
-Tracks active files (read, grep, edit, write actions).
-
 ### `tool.execute.after`
 
+- Tracks active files (read, grep, edit, write actions)
 - Tracks open errors from failed commands
 - Clears errors when commands succeed
 - Ignores `exitCode === undefined`
 
-### `compaction:before`
+### `experimental.session.compacting`
 
 Extracts workspace memory candidates from conversation, applies quality gate and deduplication.
 
+### `event`
+
+- `session.compacted`: Promote session decisions to workspace memory
+- `session.deleted`: Clean up session state files
+
 ## Debugging & Testing
 
 ### Manual Testing Steps