[Refactor] Dockerfile.non_root: drop UI drift guard approach

Revert the .dockerignore ui/ exclusion and remove the UI Drift Guard
workflow. _experimental/out/ refresh is already handled by the release
runbook; the global .dockerignore change also broke Dockerfile.custom_ui
(explicit COPY ./ui/litellm-dashboard) and the enterprise-colors inline
rebuild path in Dockerfile, Dockerfile.database, and Dockerfile.dev.

Dockerfile.non_root itself is unchanged functionally — still stages the
UI from the checked-in _experimental/out/. Only the companion workflow
and global dockerignore exclusion are dropped.

.dockerignore

@@ -52,7 +52,3 @@ build/
 *.log
 .env
 .env.local
-
-# UI source tree is not needed for the non_root image — the built output lives in
-# litellm/proxy/_experimental/out/ and is copied directly.
-ui/

.github/workflows/ui-drift-guard.yml

@@ -1,47 +0,0 @@
-name: UI Drift Guard
-permissions:
-  contents: read
-
-on:
-  pull_request:
-    branches:
-      - main
-      - litellm_internal_staging
-      - "litellm_**"
-    paths:
-      - "ui/litellm-dashboard/**"
-      - "litellm/proxy/_experimental/out/**"
-      - ".github/workflows/ui-drift-guard.yml"
-
-jobs:
-  verify-ui-output-fresh:
-    runs-on: ubuntu-latest
-    timeout-minutes: 15
-    steps:
-      - uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4.3.0
-        with:
-          persist-credentials: false
-
-      - uses: actions/setup-node@v4
-        with:
-          node-version: "20.20.2"
-          cache: "npm"
-          cache-dependency-path: ui/litellm-dashboard/package-lock.json
-
-      - name: Build UI
-        working-directory: ui/litellm-dashboard
-        run: |
-          npm ci --no-audit --no-fund
-          npm run build
-
-      - name: Compare against committed _experimental/out
-        run: |
-          set -euo pipefail
-          ( cd ui/litellm-dashboard/out && find . -type f -exec sha256sum {} + ) | sort > /tmp/fresh.txt
-          ( cd litellm/proxy/_experimental/out && find . -type f -exec sha256sum {} + ) | sort > /tmp/committed.txt
-          if ! diff -u /tmp/committed.txt /tmp/fresh.txt > /tmp/drift.txt; then
-            echo "::error::UI output is stale. Regenerate litellm/proxy/_experimental/out/ from ui/litellm-dashboard/out/."
-            head -200 /tmp/drift.txt
-            exit 1
-          fi
-          echo "UI output is fresh."

docker/Dockerfile.non_root

@@ -56,7 +56,7 @@ COPY . .
 ENV LITELLM_NON_ROOT=true
 
 # Stage the pre-built Admin UI from the checked-in Next.js static export.
-# The UI Drift Guard CI workflow keeps _experimental/out/ in sync with ui/litellm-dashboard/ source.
+# _experimental/out/ is regenerated as part of the release runbook.
 # Restructure extensionless routes (foo.html -> foo/index.html) to match the layout
 # proxy_server.py expects, and drop a readiness marker.
 RUN mkdir -p /var/lib/litellm/ui /var/lib/litellm/assets && \