Add plan-auto-show plugin to display plan after updates

When in plan mode, users couldn't see the plan without typing /plan,
but they also couldn't type /plan while being asked follow-up questions.

This plugin adds a SessionStart hook that instructs Claude to
automatically display the plan content after updating the plan file,
showing it before any follow-up questions.

Fixes the UX issue where users need to answer questions about a plan
they can't see.

plugins/plan-auto-show/settings.json

@@ -0,0 +1,15 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash ${CLAUDE_PLUGIN_ROOT}/hooks/session-start.sh"
+          }
+        ]
+      }
+    ]
+  }
+}