feat(mem0-plugin): add PostToolUseFailure, PostCompact, SessionEnd, SubagentStop hooks

Close 4 lifecycle coverage gaps:
- PostToolUseFailure: catch failed mem0 MCP calls, classify errors, inject retry guidance
- PostCompact: inject parallel search commands for context recovery after compaction
- SessionEnd: last-chance transcript capture with dedup against Stop hook
- SubagentStop: remind parent agent to persist subagent learnings

Also patch on_stop.sh to write capture marker for SessionEnd dedup.

mem0-plugin/hooks/hooks.json

@@ -132,6 +132,52 @@
           }
         ]
       }
+    ],
+    "PostToolUseFailure": [
+      {
+        "matcher": "mcp__mem0__",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/scripts/on_tool_failure.sh",
+            "timeout": 5
+          }
+        ]
+      }
+    ],
+    "PostCompact": [
+      {
+        "matcher": "manual|auto",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/scripts/on_post_compact.sh",
+            "timeout": 10
+          }
+        ]
+      }
+    ],
+    "SessionEnd": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/scripts/on_session_end.sh",
+            "timeout": 15
+          }
+        ]
+      }
+    ],
+    "SubagentStop": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/scripts/on_subagent_stop.sh",
+            "timeout": 5
+          }
+        ]
+      }
     ]
   }
 }