build exclude local dev dirs from dune watch tree

The dev server writes its SQLite database to the repo root by default. Under `dune exec -w`, each write retriggers a rebuild and restart, and the restart writes to the database again, so the server never stays up long enough to answer a request. Login and every other page returned an empty reply. Exclude local_db/ and local/ from the tree dune scans, so a relocated dev database (HITO_DB=sqlite3:local_db/hito.sqlite) no longer triggers the restart loop. Both paths are already gitignored.

Commit
54b09eed131d63aba78878a84c3d39bed7492a41
Author
Marius Peter <dev@marius-peter.com>
Author date
Committer
Marius Peter <dev@marius-peter.com>
Committer date
dune
index 00000000..d6cf85c5 000000..100644
@@ -0,0 +1,4 @@
1 Added: ; Keep local dev runtime data out of the build/watch tree. The dev server's
2 Added: ; SQLite database lives in local_db/; without this exclusion, each write
3 Added: ; retriggers `dune -w`, restarting the server in a loop.
4 Added: (dirs :standard \ local_db local)