Bump emitter package dependencies to latest versions (#38837)

Upgrades `eng/emitter-package.json` dependencies and regenerates the
lock file.

**Updated packages:**
- `@azure-tools/openai-typespec`: `1.18.0` → `1.19.0`
- `@azure-tools/typespec-ts`: `0.54.0` → `0.54.1`
- `@azure-tools/typespec-client-generator-core`: `0.68.3` → `0.68.4`

Lock file regenerated via `tsp-client generate-lock-file`.

### Packages impacted by this PR

`eng/emitter-package.json`, `eng/emitter-package-lock.json`

### Issues associated with this PR


### Describe the problem that is addressed by this PR

Emitter dependencies in `eng/emitter-package.json` were behind latest
releases. Lock file needed regeneration to match.

### What are the possible designs available to address the problem? If
there are more than one possible design, why was the one in this PR
chosen?

N/A — straightforward version bump with lock file regeneration.

### Are there test cases added in this PR? _(If not, why?)_

No — dependency version bump only; no logic changes.

### Provide a list of related PRs _(if any)_


### Checklists
- [ ] Added impacted package name to the issue description.
- [ ] Does this PR need any fixes in the SDK Generator?** _(If so,
create an Issue in the
[Autorest/typescript](https://github.com/Azure/autorest.typescript)
repository and link it here.)_
- [ ] Added a changelog (if necessary).

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: v-jiaodi <80496810+v-jiaodi@users.noreply.github.com>

Author: Copilot

eng/emitter-package-lock.json

@@ -2,15 +2,15 @@
   "name": "typescript-emitter-package",
   "main": "dist/src/index.js",
   "dependencies": {
-    "@azure-tools/openai-typespec": "1.18.0",
+    "@azure-tools/openai-typespec": "1.19.0",
     "@typespec/events": "0.82.0",
     "@typespec/openapi": "1.12.0",
     "@typespec/openapi3": "1.12.0",
     "@typespec/streams": "0.82.0",
-    "@azure-tools/typespec-ts": "0.54.0",
+    "@azure-tools/typespec-ts": "0.54.1",
     "@azure-tools/typespec-azure-core": "0.68.0",
     "@azure-tools/typespec-autorest": "0.68.0",
-    "@azure-tools/typespec-client-generator-core": "0.68.3",
+    "@azure-tools/typespec-client-generator-core": "0.68.4",
     "@azure-tools/typespec-azure-resource-manager": "0.68.0",
     "@azure-tools/typespec-azure-rulesets": "0.68.0",
     "@azure-tools/typespec-liftr-base": "0.14.0",