Automate boot unit inclusion with architecture-aware Moderne analysis

- Replace boot.mgr's static unit list with generated dangling_units.inc
- Generate Pascal LSTs and run the dangling-unit recipe before compilation
- Exclude Wasuro, inactive architectures, and NOT_DANGLING units
- Add ASURO_ARCH selection with an x86 default
- Mark unfinished legacy units as NOT_DANGLING
- Inherit pinned Moderne tooling in the builder image
- Ensure Drone pulls the latest builder image
- Document the updated build pipeline in MkDocs

Validation:
- Full x86 ISO build and VirtualBox boot succeeded
- 1,133 kernel tests passed with no failures
- x86_64 build failed clearly due to unavailable sources

.drone.yml

@@ -17,6 +17,7 @@ steps:
 
   - name: compile
     image: t3hn3rd/asuro-build:latest
+    pull: always
     depends_on:
       - build-image
     commands: