Drop the integrationsdotsh submodule too — executor tracks zero submodules now

integrationsdotsh is a downstream product that consumes executor's published
SDK, not something executor imports. There was no gitlink — just a phantom
.gitmodules entry plus a few "ignore this dir" guards. Develop it in its own
repo (github.com/RhysSullivan/integrationsdotsh) like the forks.

- Remove the integrationsdotsh stanza from .gitmodules (its last entry, so the
  file is deleted — executor has no submodules now)
- Drop the now-stale integrationsdotsh ignores in .oxlintrc.jsonc, .oxfmtrc.json,
  and scripts/migrate-schema-class.ts

Author: RhysSullivan

.gitmodules

@@ -7,7 +7,6 @@
     "dist",
     "vendor",
     "e2e/runs",
-    "integrationsdotsh",
     "node_modules",
     "packages/core/fumadb",
     "bun.lock",

.oxfmtrc.json

@@ -153,7 +153,6 @@
     "vendor/",
     "emulators/",
     "e2e/runs/",
-    "integrationsdotsh/",
     "node_modules/",
     "packages/core/fumadb/",
     "packages/core/sdk/src/vendor/json-schema-to-typescript/",

.oxlintrc.jsonc

@@ -30,7 +30,6 @@ const IGNORE_DIRS = new Set([
   "build",
   ".local",
   ".changeset",
-  "integrationsdotsh",
 ]);
 
 // Files we intentionally leave alone — they contain `Schema.Class` strings as