ci(linux): weekly soak run for build-linux + workflow_dispatch

Adds a weekly schedule (Mondays 14:13 UTC, off the :00 minute) and
manual workflow_dispatch trigger to the Linux workflow. While the
work still lives on the linux branch (pre-merge), scheduled runs
explicitly check out ref=linux; push/pull_request runs keep the
natural ref via a github.event_name conditional.

Picks up the testcontainers integration tests automatically since the
integration job already runs them with --include-ignored.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: datlechin

.github/workflows/build-linux.yml

@@ -10,6 +10,9 @@ on:
     paths:
       - "linux/**"
       - ".github/workflows/build-linux.yml"
+  schedule:
+    - cron: "13 14 * * 1"
+  workflow_dispatch:
 
 jobs:
   fast:
@@ -20,6 +23,8 @@ jobs:
         working-directory: linux
     steps:
       - uses: actions/checkout@v5
+        with:
+          ref: ${{ github.event_name == 'schedule' && 'linux' || github.ref }}
       - name: Install system dependencies
         run: |
           sudo apt-get update
@@ -55,6 +60,8 @@ jobs:
         working-directory: linux
     steps:
       - uses: actions/checkout@v5
+        with:
+          ref: ${{ github.event_name == 'schedule' && 'linux' || github.ref }}
       - name: Install system dependencies
         run: |
           sudo apt-get update