build(ci): drop github-slug-action, compute short SHA inline

Replace the third-party rlespinasse/github-slug-action with inline shell
to compute the 8-char short SHA, removing a CI supply-chain dependency.

build-image and deploy-prod use ${GITHUB_SHA:0:8} (the auto-injected
default env var, no template interpolation). deploy-dev keeps the shell
approach off github.event.pull_request.head.sha, since on pull_request
triggers GITHUB_SHA is the merge commit, not the PR head.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: LoneRifle

.github/workflows/build-image.yml

@@ -63,7 +63,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@797d68864753cbceedc271349d402da4590e6302 # v4.5.0
+        run: echo "GITHUB_SHA_SHORT=${GITHUB_SHA:0:8}" >> $GITHUB_ENV
 
       - name: Build and Publish Docker Image with DB
         uses: docker/build-push-action@ca052bb54ab0790a636c9b5f226502c73d547a25 # v5
@@ -124,7 +124,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@797d68864753cbceedc271349d402da4590e6302 # v4.5.0
+        run: echo "GITHUB_SHA_SHORT=${GITHUB_SHA:0:8}" >> $GITHUB_ENV
 
       - name: Build and Publish Docker Image without DB
         uses: docker/build-push-action@ca052bb54ab0790a636c9b5f226502c73d547a25 # v5

.github/workflows/deploy-dev.yml

@@ -27,7 +27,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_PASSWORD }}
 
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4.5.0
+        run: echo "GITHUB_EVENT_PULL_REQUEST_HEAD_SHA_SHORT=$(echo ${{ github.event.pull_request.head.sha }} | cut -c 1-8)" >> $GITHUB_ENV
 
       - name: Set GITHUB_SHA_SHORT from PR
         if: env.GITHUB_EVENT_PULL_REQUEST_HEAD_SHA_SHORT != null

.github/workflows/deploy-prod.yml

@@ -30,7 +30,7 @@ jobs:
         uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
 
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@797d68864753cbceedc271349d402da4590e6302 # v4.5.0
+        run: echo "GITHUB_SHA_SHORT=${GITHUB_SHA:0:8}" >> $GITHUB_ENV
 
       - name: Build and Publish HuggingChat image
         uses: docker/build-push-action@ca052bb54ab0790a636c9b5f226502c73d547a25 # v5
@@ -54,7 +54,7 @@ jobs:
     needs: ["build-and-publish-huggingchat-image"]
     steps:
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@797d68864753cbceedc271349d402da4590e6302 # v4.5.0
+        run: echo "GITHUB_SHA_SHORT=${GITHUB_SHA:0:8}" >> $GITHUB_ENV
 
       - name: Gen values
         run: |