project_panel: Add auto_open settings (#40435)

- Based on #40234, and improvement of #40331

Release Notes:

- Added granular settings to control when files auto-open in the project
panel (project_panel.auto_open.on_create, on_paste, on_drop)

<img width="662" height="367" alt="Screenshot_2025-10-16_17-28-31"
src="https://github.com/user-attachments/assets/930a0a50-fc89-4c5d-8d05-b1fa2279de8b"
/>

---------

Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>

docs/src/configuring-zed.md

@@ -4280,7 +4280,11 @@ Run the {#action theme_selector::Toggle} action in the command palette to see a
     "hide_root": false,
     "hide_hidden": false,
     "starts_open": true,
-    "open_file_on_paste": true
+    "auto_open": {
+      "on_create": true,
+      "on_paste": true,
+      "on_drop": true
+    }
   }
 }
 ```
@@ -4489,6 +4493,26 @@ Run the {#action theme_selector::Toggle} action in the command palette to see a
 }
 ```
 
+### Auto Open
+
+- Description: Control whether files are opened automatically after different creation flows in the project panel.
+- Setting: `auto_open`
+- Default:
+
+```json [settings]
+"auto_open": {
+  "on_create": true,
+  "on_paste": true,
+  "on_drop": true
+}
+```
+
+**Options**
+
+- `on_create`: Whether to automatically open newly created files in the editor.
+- `on_paste`: Whether to automatically open files after pasting or duplicating them.
+- `on_drop`: Whether to automatically open files dropped from external sources.
+
 ## Agent
 
 Visit [the Configuration page](./ai/configuration.md) under the AI section to learn more about all the agent-related settings.