feat(graceful-handoff): 2.0 — register hooks and statusLine in hooks.json [skip-docs]

Step 7 of v2.0 plan. Registers SessionStart, Stop, and statusLine hooks.
Note: statusLine top-level placement in hooks.json is an open assumption
(brief Assumption 1) — verified to be valid JSON syntax; live smoke-test
required to confirm Claude Code loads it from this location vs requiring
settings.json placement.

plugins/graceful-handoff/hooks/hooks.json

@@ -0,0 +1,31 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "node ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/session-start-load-handoff.mjs",
+            "timeout": 5
+          }
+        ]
+      }
+    ],
+    "Stop": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "node ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/stop-context-monitor.mjs",
+            "timeout": 30
+          }
+        ]
+      }
+    ]
+  },
+  "statusLine": {
+    "type": "command",
+    "command": "node ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/statusline-monitor.mjs",
+    "padding": 0
+  }
+}