ADR 0030 Phases B+C: stage-1 initramfs and the RT kernel become packages of the one build

.github/actions/README.md

@@ -2,17 +2,15 @@
 
 | Action | Owns | Called by | Notes |
 |--------|------|-----------|-------|
-| **buildroot-build** | Runner prep (disk, apt, five caches) + `make all` (main) or `make <variant>` (kernel-only). Outputs: `output/images/` or `output-<name>/images/` + legal-info on demand. | build.yml, release.yml, reproducibility.yml | Single source of truth for the Buildroot recipe across three workflows. main's cache key strings are byte-identical to before the variant input existed; existing cache entries keep hitting. Kernel variants derive their own cache namespaces from fragment existence. |
-| **kernel-leg** | One kernel-variant matrix leg: build via buildroot-build, render job summary, stage artifact (zImage_dtb + .config + modules tar + legal-info), upload for `build` to merge. | build.yml (build-kernel matrix), release.yml (build-kernel matrix) | Moves the 72-identical shared lines from build.yml and release.yml's own copies. Inputs: kernel, full-legal-info, release-context. |
-| **merge-kernel-modules** | Two phases: (1) phase=download: download kernel-leg artifacts, populate work/extra-modules-overlay/ (runs BEFORE buildroot-build); (2) phase=verify: assert every kver merged into output/target/ (runs AFTER buildroot-build). | build.yml, release.yml | Phase-gated input enforces sequence discipline and prevents silent overlay misses. Called twice per workflow (download then verify). |
+| **buildroot-build** | Runner prep (disk, apt, caches) + `make all`. Outputs: `output/images/` (linux.img, zImage_dtb, zImage_dtb-rt, mister-initramfs.cpio) + legal-info on demand. Since ADR 0030 Phase C the RT kernel and the stage-1 initramfs are packages of the one build, so there is no kernel-only variant mode any more (the `variant` input errors on anything but `main`). | build.yml, release.yml, reproducibility.yml | Single source of truth for the Buildroot recipe across three workflows. main's cache key strings are byte-identical to before the variant input existed; existing cache entries keep hitting. Kernel variants derive their own cache namespaces from fragment existence. |
 | **verify-image** | Run parity suite (P3.12) + ABI/SONAME checker (P2.2) against built image. Uploads results artifact on every run (`if: always()`). | build.yml, release.yml | Input: skip-qemu-system (default "true" — byte-identical to old hard-coded "1"). Both workflows used to carry identical copies. |
 
 ## Rule: When to Add a Fifth Action
 
 **Only add a new composite action when ALL of these hold:**
 1. The work is genuinely self-contained (no dependencies within another action's phase).
 2. Its failure modes are independent (a failure does NOT require coordination with an existing action's state).
-3. No workflow sequence rule applies (if two actions must run in order with state between them, use a phase input instead — see `merge-kernel-modules`).
+3. No workflow sequence rule applies (if two actions must run in order with state between them, use a phase input instead).
 
 **Otherwise, extend an existing action via inputs.**