docs(g15d): add blockvolume launcher mini-plan

sw-block/design/v3-phase-15-g15d-blockvolume-launcher-mini-plan.md

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+# V3 Phase 15 G15d Mini-Plan — BlockVolume Launcher MVP
+
+Date: 2026-05-03
+Status: first pure-planner slice landed on `p15-g15d/blockvolume-launcher`
+Depends on: G15c `CreateVolume -> lifecycle desired intent`
+
+## 0. Product Sentence
+
+G15d turns dynamic volume intent into runnable blockvolume workloads. It keeps the current safe runtime model — one blockvolume process per volume replica — and adds the missing orchestration layer that makes Kubernetes dynamic provisioning real.
+
+## 1. Why This Gate Exists
+
+G15c can record a desired volume from CSI `CreateVolume`, but no component yet starts the blockvolume daemon(s) that serve that volume. Without G15d, a dynamic PVC can create intent but cannot become mountable.
+
+Do not solve this by making `blockvolume` multi-volume in one step. That is a larger runtime refactor. The MVP path is:
+
+```text
+PVC
+  -> CSI CreateVolume
+  -> master lifecycle desired volume
+  -> launcher creates blockvolume workload(s)
+  -> blockvolume heartbeat
+  -> product loop verifies placement
+  -> publisher assignment
+  -> CSI publish/stage/mount
+```
+
+## 2. Scope
+
+IN:
+- Pure workload planner: desired volume + placement + node inventory -> blockvolume workload intent.
+- Anti-authority shape tests: workload plans cannot carry epoch, endpoint_version, primary, ready, or healthy.
+- Idempotency tests.
+- Later slice: K8s manifest renderer / apply loop.
+- Later slice: M02 dynamic PVC smoke.
+
+OUT:
+- Multi-volume blockvolume daemon.
+- K8s operator framework.
+- Scheduling policy beyond existing lifecycle placement.
+- Authority minting from launcher.
+- Replica readiness or primary selection.
+
+## 3. First Slice Evidence
+
+Commit: `56a1047 G15d: add blockvolume workload planner`
+
+Implemented:
+- `core/lifecycle.BlockVolumeWorkloadPlan`
+- `PlanBlockVolumeWorkloads`
+- Tests:
+  - blank-pool RF=2 creates deterministic replica workload intents
+  - existing replica keeps replica ID
+  - same inputs are idempotent
+  - workload plan structs are not authority-shaped
+
+Verification:
+
+```powershell
+go test ./core/lifecycle -count=1
+```
+
+## 4. Next Slices
+
+G15d-B — K8s spec renderer:
+- Convert `BlockVolumeWorkloadPlan` to deterministic K8s Deployment/StatefulSet-like spec data.
+- Keep renderer pure; no cluster client yet.
+- Test generated args include `--volume-id`, `--replica-id`, `--data-addr`, `--ctrl-addr`, durable root, and optional iSCSI listen.
+
+G15d-C — Apply loop:
+- Add a narrow launcher runner that applies generated workload specs.
+- First implementation may shell `kubectl apply -f` or write manifests for QA to apply.
+- It must be idempotent.
+
+G15d-D — M02 dynamic PVC:
+- `StorageClass` + PVC without hand-written PV.
+- external-provisioner calls CSI CreateVolume.
+- launcher starts blockvolume workload.
+- pod writes 4 KiB + sync + checksum read-back OK.
+
+## 5. Close Criteria
+
+G15d closes only when M02 proves dynamic PVC smoke without a pre-created PV and without hand-started blockvolume for that PVC.