chore: share the project setup and actions through .openchamber/project.json

Track the worktree setup command, the DevHMR project action and the plans
directory so they follow the repository; screenshots stay ignored.

.gitignore

@@ -70,7 +70,7 @@ workspaces/
 .worktrees/
 
 # OpenChamber app runtime state (sessions db, screenshots)
-.openchamber/
+.openchamber/screenshots/
 
 # Marks a disposable clone dedicated to unattended maintenance tasks.
 .maintenance-clone

.openchamber/project.json

@@ -0,0 +1,15 @@
+{
+  "version": 1,
+  "setupWorktree": [
+    "bun install"
+  ],
+  "projectActions": [
+    {
+      "id": "5525a5ee-9c03-44d1-a401-1e4b9397765c",
+      "name": "DevHMR",
+      "command": "bun run dev:web:hmr",
+      "icon": "rocket"
+    }
+  ],
+  "plansDir": ".openchamber/plans"
+}