ci: sync workflow fixes from main into release-1.10.0 (fix broken nightly) (#13400)

ci: sync workflow fixes from main into release-1.10.0

Brings the latest CI/workflow fixes from main into release-1.10.0 so the
nightly build is unblocked and the two branches share the same hardening.

Most important fix: release_nightly.yml's "Verify Nightly Name and Version"
step now uses the anchored grep '^langflow(-nightly)?[[:space:]]' instead of
'grep langflow | grep -v langflow-base | grep -v langflow-sdk'. The old
filter started matching two packages once the langflow-stepflow workspace
package was added, so the name became multi-line and the check failed
(this is what broke the nightly build).

Also carries main's fixes for cross-platform install
(--prerelease=if-necessary-or-explicit), docker build workflows,
db-migration-validation, and the backend test timeout bump (30 -> 40).
3-way merged from the common ancestor, so release-only changes are
preserved; no release-only feature workflows are modified.

.github/workflows/python_test.yml

@@ -93,7 +93,7 @@ jobs:
       - name: Run unit tests
         uses: nick-fields/retry@v3
         with:
-          timeout_minutes: 30
+          timeout_minutes: 40
           max_attempts: 2
           command: make unit_tests args="-x -vv --splits ${{ matrix.splitCount }} --group ${{ matrix.group }} --reruns 5 --cov --cov-config=src/backend/.coveragerc --cov-report=xml --cov-report=html"