Restore test devDependencies dropped from two vendor overlays

The intx-agent and intx-tools-posix overlays dropped upstream's
@intx/storage-isogit devDependency, leaving their eight vendored test
files resolving it only through the root's hoisted link. Restore the
devDependencies mapped to workspace:* like the trio overlays, and fix
the VENDORING.md example to cite @intx/tools-lsp, which remains
npm-published, instead of the now-vendored @intx/agent.

Author: TheGreatAxios

bun.lock

@@ -94,7 +94,7 @@ including nested Bun package layouts such as
 `node_modules/.bun/@intx+agent@…/node_modules/@intx/types` — at the
 vendored tree. That is the runtime and install-time story.
 
-TypeScript needs a second pin. Published packages such as `@intx/agent@0.3.0`
+TypeScript needs a second pin. Published packages such as `@intx/tools-lsp`
 ship `dist/*.d.ts` that import `@intx/types/runtime`. When a stale or
 partial install leaves a nested published `@intx/types@0.3.0` (with its
 older `dist/` shapes, missing fields such as `PendingOperation.kind`),

docs/VENDORING.md

@@ -19,5 +19,8 @@
     "@intx/mime": "0.3.0",
     "@intx/types": "workspace:*",
     "arktype": "catalog:"
+  },
+  "devDependencies": {
+    "@intx/storage-isogit": "workspace:*"
   }
 }

vendor/intx-agent/package.json

@@ -16,5 +16,8 @@
   "dependencies": {
     "@intx/agent": "workspace:*",
     "@intx/types": "workspace:*"
+  },
+  "devDependencies": {
+    "@intx/storage-isogit": "workspace:*"
   }
 }