docs: put MinIO first-class on ground, add executive overview

Treat MinIO as existing stack infrastructure (default T3 warehouse, not
on the drone), add a one-page executive map, and record placement as an
open team question rather than a rip-and-replace.

docs/08-roadmap.md

@@ -9,11 +9,11 @@ graph TD
     S1["Stage 1<br/>Dev environment + CI skeleton<br/>Dev Containers, GitLab templates, multi-arch builds"]
     S2["Stage 2<br/>Registry and artifacts<br/>images, model weights, schemas, cleanup policies"]
     S3["Stage 3<br/>Single-drone data pipeline<br/>ingest → current/ → sealed Parquet → DuckDB"]
-    S4["Stage 4<br/>Serving layer<br/>event hook, query API, local MinIO"]
+    S4["Stage 4<br/>Serving layer<br/>event hook, query API"]
     S5["Stage 5<br/>Virtual swarm simulation<br/>N drones in Compose, seeded scenarios, CI regression"]
     S6["Stage 6<br/>Mesh network and security<br/>WireGuard overlay, PKI provisioning, mTLS"]
-    S7["Stage 7<br/>Swarm sync<br/>pose broadcast, detections pub/sub, MinIO replication"]
-    S8["Stage 8<br/>Ground warehouse<br/>offload + audit, T3 store, replay tooling"]
+    S7["Stage 7<br/>Swarm sync<br/>pose broadcast, detections pub/sub, bulk pull"]
+    S8["Stage 8<br/>Ground warehouse<br/>offload + audit, MinIO T3, replay tooling"]
     S9["Stage 9<br/>Observability<br/>platform metrics as sensor stream, ground dashboards"]
     S10["Stage 10<br/>Fleet releases<br/>manifest, mirror, dock delivery, atomic rollback"]
     S11["Stage 11<br/>Query standard<br/>GraphQL contract, schema registry, multi-team surface"]
@@ -41,11 +41,11 @@ graph TD
 | **1 — Dev environment + CI skeleton** | Dev Containers, GitLab shared templates, multi-arch runner fleet | An engineer builds and tests on day one; ARM64/AMD64 both green | — |
 | **2 — Registry & artifacts** | GitLab registry live, model weights + schemas as versioned packages | One artifact store, scanning wired in (Trivy, SonarQube) | 1 |
 | **3 — Single-drone data pipeline** | `sensor-ingest` → writer → `current/` → sealed → DuckDB queries on one node | The storage core: rates sustained, compression measured, quotas enforced | 1 |
-| **4 — Serving layer** | Event hook + query API + on-board MinIO | Event-driven consumption; nothing polls | 3 |
+| **4 — Serving layer** | Event hook + query API (SQL gate) | Event-driven consumption; nothing polls | 3 |
 | **5 — Virtual swarm** | Simulator, N drones via Compose, seeded scenarios, CI regression gate | Everything after this ships with a test bench | 2, 4 |
 | **6 — Mesh & security** | WireGuard overlay, offline CA, provisioning flow, mTLS | Zero-trust fabric exists before any real sync traffic | 1 |
-| **7 — Swarm sync** | Pose broadcast + detections pub/sub + bulk replication over the mesh | Staleness budgets met under simulated loss/partitions | 5, 6 |
-| **8 — Ground warehouse** | Dock offload (mirror + audit), T3 store, replay queries | A full flight round-trips: fly (simulated) → offload → replay | 3 |
+| **7 — Swarm sync** | Pose broadcast + detections pub/sub + bulk partition pull | Staleness budgets met under simulated loss/partitions | 5, 6 |
+| **8 — Ground warehouse** | Dock offload (mirror + audit), **MinIO as T3**, replay queries | A full flight round-trips: fly (simulated) → offload → replay | 3 |
 | **9 — Observability** | Platform metrics as sensor stream; ground Prometheus/Grafana/Loki; post-mortem dashboards | Every health question from [07](07-observability.md) answerable | 7, 8 |
 | **10 — Fleet releases** | Release manifest, registry mirror, dock delivery, atomic rollback drill | The whole fleet moves as one version, rollback rehearsed | 2, 5 |
 | **11 — Query standard** | GraphQL contract over versioned schemas; documentation for other teams | The multi-team integration surface | 7, 8 |