ci: unified firmware manifest for release discovery

Replace the two-tier approach (per-release manifest + top-level index)
with a single unified manifest containing all releases and their builds
inline. This allows QGC to fetch one file to find firmware for any board
across all releases, avoiding the need to fetch many per-release manifests.

Schema uses format_version 2 with releases as a dict keyed by version
for O(1) upserts. The manifest is stored at s3://px4-travis/Firmware/manifest.json
and updated on every CI build (tags + main/stable/beta branches).

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

.github/workflows/build_all_targets.yml

@@ -210,6 +210,10 @@ jobs:
     outputs:
       uploadlocation: ${{ steps.upload-location.outputs.uploadlocation }}
     steps:
+      - uses: actions/checkout@v4
+        with:
+          sparse-checkout: Tools/manifest
+
       - name: Download Artifacts
         uses: actions/download-artifact@v4
         with:
@@ -269,4 +273,57 @@ jobs:
             artifacts/*.px4
             artifacts/*.deb
             artifacts/**/*.sbom.spdx.json
+            manifest.json
           name: ${{ steps.upload-location.outputs.uploadlocation }}
+
+      # Update the unified firmware manifest with this release
+      # The manifest lives at s3://px4-travis/Firmware/manifest.json and provides
+      # a complete index of all releases and builds for tools like QGroundControl
+      - name: Backup Existing Firmware Manifest
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          s3_base="https://px4-travis.s3.us-west-1.amazonaws.com/Firmware"
+          mkdir -p manifest_backup
+          curl -sf "${s3_base}/manifest.json" -o manifest_backup/manifest.json.backup || echo "No existing manifest to backup"
+          if [ -f manifest_backup/manifest.json.backup ]; then
+            echo "Backed up existing firmware manifest ($(wc -c < manifest_backup/manifest.json.backup) bytes)"
+          fi
+
+      - name: Upload Firmware Manifest Backup
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: actions/upload-artifact@v4
+        with:
+          name: firmware_manifest_backup_${{ steps.upload-location.outputs.uploadlocation }}
+          path: manifest_backup/
+          if-no-files-found: ignore
+          retention-days: 90
+
+      - name: Update Firmware Manifest
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          version="${{ steps.upload-location.outputs.uploadlocation }}"
+          git_tag=""
+          base_url=""
+          s3_base="https://px4-travis.s3.us-west-1.amazonaws.com/Firmware"
+
+          if [[ "$GITHUB_REF" == refs/tags/v* ]]; then
+            git_tag="${GITHUB_REF#refs/tags/}"
+            base_url="https://github.com/${{ github.repository }}/releases/download/${git_tag}"
+          fi
+
+          python3 ./Tools/manifest/update_firmware_manifest.py \
+            --dir artifacts/ \
+            --version "$version" \
+            --git-tag "$git_tag" \
+            --base-url "$base_url" \
+            --fetch-url "${s3_base}/manifest.json" \
+            --out manifest.json
+
+      - name: Upload Firmware Manifest to S3
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          aws s3 cp manifest.json s3://px4-travis/Firmware/manifest.json --acl public-read
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_REGION: 'us-west-1'