Make sure it does not try to open a DB Graph!

Nobody has claimed this yet.

### Search first

- [x] I searched and no similar issues were found

### What Happened?

I use the File Graph (OG) version for my daily journal and notes and test the new DB Version.

When i had opened the DB version of Logseq and then open the OG version again, it tries to open the previously opened DB Graph (and fails).

### Reproduce the Bug

0. have used Logseq DB
1. use OG again

### Expected Behavior

It should not try to open it and potentially corrupt the data, but check the format and give an error "Graph not compatible. Open it with the new DB version." Let the user select a different graph from "all graphs".

### Screenshots

_No response_

### Desktop or Mobile Platform Information

NixOS 25.11.6495.e764fc9a4058
logseq-0.10.14
Logseq 2.0.1 (todays latest build)

### Additional Context

The DB version has the same issue: https://github.com/logseq/db-test/issues/763

Terminal output of this issue:

```
[davidak@gaming:~]$ logseq
(rsapi) init loggers
23:57:37.120 › Logseq App(0.10.14) Starting...
23:57:37.125 › restore proxy settings {:type "system"}
23:57:37.126 › set proxy to {:type "system"}
[2026-03-02 23:57:37.145] [MANGOHUD] [error] [overlay_params.cpp:151] Unrecognized key: 'none'
[2026-03-02 23:57:37.164] [MANGOHUD] [info] [gpu.cpp:89] Set renderD128 as active GPU (driver=nvidia id=10de:2786 pci_dev=0000:01:00.0)
23:57:39.576 › :electron.handler/watch-dir {:path "/home/davidak/.logseq/config"}
23:57:39.614 › :electron.handler/unwatch-dir {:path "/logseq_db_Test"}
23:57:39.614 › :electron.handler/watch-dir {:path "/logseq_db_Test"}
23:57:39.616 › IPC error: {:event #object[Event [object Object]], :args #js ["readdir" "/logseq_db_Test"]} Error: ENOENT: no such file or directory, scandir '/logseq_db_Test'
at Object.readdirSync (node:fs:1597:26)
at t.readdirSync (node:electron/js2c/node_init:2:16044)
at /nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:14000:64
at /nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:5000:28
at $JSCompiler_StaticMethods_sval$$ (/nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:3249:301)
at $JSCompiler_prototypeAlias$$.$cljs$core$ISeqable$_seq$arity$1$ (/nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:3323:3)
at $cljs$core$seq$$ (/nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:1524:40)
at /nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:4971:54
at $JSCompiler_StaticMethods_sval$$ (/nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:3249:301)
at $JSCompiler_prototypeAlias$$.$cljs$core$ISeqable$_seq$arity$1$ (/nix/store/22avx8s27mmc6p0bwnlva5ffm3989xl8-logseq-0.10.14/share/logseq/resources/app/electron.js:3323:3)
23:58:35.752 › :electron.handler/watch-dir {:path "/home/davidak/info/notes-logseq"}
```

### Are you willing to submit a PR? If you know how to fix the bug.

- [ ] I'm willing to submit a PR (Thank you!)

Reproduce the switch from the DB version to the OG version using the listed steps and inspect the startup sequence around the reported watch-dir and ENOENT output in electron.js. Trace how the previously opened graph is selected and checked. Done means an incompatible DB graph is rejected with the stated error and the user can choose another graph from “all graphs”.

Written by the indexing model from the issue text.