fix: Disable port auto-detection, forward 8000 explicitly

VS Code's auto-detection races with sphinx-autobuild on container
restart and steals the port, breaking the live-reload docs preview.
Disable it and forward 8000 explicitly so the docs URL is stable.

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

Author: gilesknap

.devcontainer/devcontainer.json

@@ -31,7 +31,10 @@
                 "python.terminal.activateEnvironment": false,
                 // Workaround to prevent garbled python REPL in the terminal
                 // https://github.com/microsoft/vscode-python/issues/25505
-                "python.terminal.shellIntegration.enabled": false
+                "python.terminal.shellIntegration.enabled": false,
+                // Only forward explicitly listed ports — auto-detection races with
+                // sphinx-autobuild and steals the port on restart
+                "remote.autoForwardPorts": false
             },
             // Add the IDs of extensions you want installed when the container is created.
             "extensions": [
@@ -45,7 +48,11 @@
             ]
         }
     },
-    // Create the config folder for the bash-config feature and uv cache
+    // Explicitly forward sphinx-autobuild port (auto-detection disabled above)
+    "forwardPorts": [
+        8000
+    ],
+    // Create host-side dirs needed for bind mounts before the container starts
     "initializeCommand": "mkdir -p ${localEnv:HOME}/.config/terminal-config",
     "runArgs": [
         // Allow the container to access the host X11 display and EPICS CA