Integrate publish-documentation into release workflow; remove push auto-trigger (#169)

`publish-documentation.yml` was firing automatically on every push to
`release/**`, running independently from `release.yml` and outside the
controlled release pipeline.

## Changes

**`publish-documentation.yml`**
- Replaced `push` trigger with `workflow_call` — workflow is now
exclusively driven by `release.yml` or manual dispatch
- `workflow_dispatch` retained for on-demand runs

**`release.yml`**
- Added `publish-documentation` job between `pack` and
`publish-package`:
  - Depends on `pack` + `validate-release`
- Gated with `if: is-release == 'true'` — skipped on `preview/**`
branches
- Calls `./.github/workflows/publish-documentation.yml` with explicit
`pages: write` + `id-token: write` permissions
- Updated `publish-package` to depend on `publish-documentation` with an
`always()`-based condition to handle the `skipped` result on preview
branches, preventing the gate from blocking NuGet publishing:

```yaml
publish-package:
  needs: [pack, validate-release, publish-documentation]
  if: >-
    always() &&
    needs.pack.result == 'success' &&
    needs.validate-release.result == 'success' &&
    (needs.publish-documentation.result == 'success' || needs.publish-documentation.result == 'skipped')
```

Author: Copilot

.github/workflows/publish-documentation.yml

@@ -2,12 +2,7 @@
 
 on:
   workflow_dispatch:
-  push:
-    branches:
-      - 'release/**'
-    paths:
-      - 'src/**'
-      - 'api-reference/**'
+  workflow_call:
 
 permissions:
   actions: read

.github/workflows/release.yml

@@ -206,9 +206,20 @@ jobs:
             ${{ runner.temp }}/${{ env.nuget-packages-directory }}/**/*.nupkg
             ${{ runner.temp }}/${{ env.nuget-packages-directory }}/**/*.snupkg
 
+  publish-documentation:
+    name: 'Publish documentation'
+    needs: [pack, validate-release, workflow-variables]
+    if: ${{ needs.workflow-variables.outputs.is-release == 'true' }}
+    uses: ./.github/workflows/publish-documentation.yml
+    permissions:
+      actions: read
+      pages: write
+      id-token: write
+
   publish-package:
     name: 'Publish package'
-    needs: [pack, validate-release]
+    needs: [pack, validate-release, publish-documentation]
+    if: ${{ always() && needs.pack.result == 'success' && needs.validate-release.result == 'success' && (needs.publish-documentation.result == 'success' || needs.publish-documentation.result == 'skipped') }}
     env:
       package-artifact-name: ${{ needs.pack.outputs.package-artifact-name }}
     runs-on: ubuntu-latest