feat: add hooks to plugin.json, eliminating need for global install

The beads plugin now provides SessionStart and PreCompact hooks directly
via plugin.json. Users no longer need to run 'bd setup claude' when using
the plugin - hooks are automatically available.

Changes:
- Add hooks section to .claude-plugin/plugin.json with SessionStart and
  PreCompact hooks that run 'bd prime'
- Update doctor/claude.go to recognize plugin-provided hooks as valid
- Update tips.go to check for plugin installation when determining if
  Claude integration is complete
- Update messaging to recommend plugin installation as primary option

The 'bd setup claude' command remains available for CLI-only users who
do not want to install the plugin.

Closes #462

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.claude-plugin/plugin.json

@@ -27,5 +27,29 @@
       ],
       "env": {}
     }
+  },
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bd prime"
+          }
+        ]
+      }
+    ],
+    "PreCompact": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bd prime"
+          }
+        ]
+      }
+    ]
   }
 }