plan: give realistic buildings their own minor milestone (0.9.0)

The facade work started as a patch (0.1.4) and the 0.1.6 retail pass showed what
that costs: a patch has no release gate of its own, so a first pass that does not
yet read as the building can sit inside a done patch series. Realism is also the
leading quality goal, which a patch cannot carry.

New 0.9.0 - Realistic buildings, before the feature freeze: facade system with more
than one order, a profile library, storefront types, signage as decals, per-building
photo-matched models, a measured material library with a texel-density rule, and
LODs plus collision proxies. Former 0.9.0 freeze/beta/audit becomes 0.10.0 with
patches 0.10.1-0.10.3; 1.0.0 moves to weeks 39-44.

Recorded as ADR-8 (append-only) with a measurable gate BR-1..BR-5 in the quality
requirements, mirrored into the combined architecture.md. The 0.1.6 item now says
which of its gaps move to 0.9.0 and why more geometry cannot close them.

PLAN.md

@@ -108,8 +108,9 @@ Solo-development estimate: **approximately 30–40 weeks**, subject to asset qua
 | `0.6.0` | 22–24 | Visual/audio pass and evening lighting preset | `0.6.1` lighting fixes; `0.6.2` material corrections; `0.6.3` audio balancing |
 | `0.7.0` | 25–27 | Settings, control rebinding, save/load, accessibility basics | `0.7.1` save fixes; `0.7.2` UI fixes; `0.7.3` input persistence fixes |
 | `0.8.0` | 28–30 | Performance budgets and broader Linux hardware testing | `0.8.1` VRAM reductions; `0.8.2` frame-time fixes; `0.8.3` compatibility fixes |
-| `0.9.0` | 31–34 | Feature freeze, public beta, license and build audit | `0.9.1` blocker fixes; `0.9.2` regression fixes; `0.9.3` documentation fixes |
-| `1.0.0` | 35–40 | Stable neighborhood-scale walking/driving release | `1.0.x` maintenance and compatibility fixes |
+| `0.9.0` | 31–34 | Realistic buildings: façade system, per-building models, measured material library, LODs and collision proxies | `0.9.1` façade fixes |
+| `0.10.0` | 35–38 | Feature freeze, public beta, license and build audit | `0.10.1` blocker fixes; `0.10.2` regression fixes; `0.10.3` documentation fixes |
+| `1.0.0` | 39–44 | Stable neighborhood-scale walking/driving release | `1.0.x` maintenance and compatibility fixes |
 
 Finish each milestone's release checks before expanding scope. Cut map size and simulation complexity before compromising the core walking/driving experience.