docs: mark Phase N.1 shipped + file road-edge tree as known issue

Adds Phase N.1 to "Phases already shipped" table at top of roadmap,
updates the Phase N section to mark N.1 with checkmark SHIPPED status,
and files the known road-edge-tree cosmetic difference at landblock
0xA9B1 in ISSUES.md as issue #50 follow-up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/plans/2026-04-11-roadmap.md

@@ -57,6 +57,7 @@
 | K | Input architecture — `Action` enum, `KeyChord`, `KeyBindings`, multicast `InputDispatcher` with scope-stack + modal capture, retail-default keymap (152 bindings), `keybinds.json` persistence, F11 Settings panel with click-to-rebind + conflict detection, main menu bar + View menu | Live ✓ |
 | L.0 | Full retail-style Settings interface — F11 tabbed panel with 6 tabs (Keybinds + Display + Audio + Gameplay + Chat + Character). `settings.json` at `%LOCALAPPDATA%\acdream\`, per-toon `Character` keying (swapped on EnterWorld). Display GL knobs (Resolution / Fullscreen / VSync / FOV / ShowFps) + Audio (Master / SFX) live-wired; Gameplay / Chat / Character settings persist for server-sync wiring later. Tab API extension to `IPanelRenderer`; chat Copy mode (read-only multi-line); per-panel layout reset; FramebufferResize handler keeps GL viewport + camera aspect + panel positions in sync. | Live ✓ |
 | C.1 | PES particle system + sky-pass refinements — retail-faithful `ParticleEmitterInfo` unpack with all 13 motion integrators (`Particle::Init`/`Update` ports of `0x0051c290`/`0x0051c930`), `PhysicsScriptRunner` with `CallPES` self-loop semantics, `ParticleHookSink` with `EmitterDied` cleanup, instanced billboard `ParticleRenderer` with material-derived blend (DAT emitters never default additive — pulled from particle GfxObj surface), global back-to-front sort, BC clipmap alpha-keying, AttachLocal `is_parent_local=1` live-parent follow via `UpdateEmitterAnchor`. Sky pass: `Translucent+ClipMap` → alpha-blend cloud sheet (matches `D3DPolyRender::SetSurface` `0x0059c4d0`), raw-`Additive` fog-skip (matches `0x0059c882`), per-keyframe `SkyObjectReplace` Translucency/Luminosity/MaxBright divide-by-100, bit `0x01` pre/post-scene split (matches `GameSky::CreateDeletePhysicsObjects` `0x005073c0`), Setup-backed (`0x020xxxxx`) sky objects via `SetupMesh.Flatten`, persistent GL sampler objects (Wrap + ClampToEdge) replace per-frame wrap-mode mutation (ported from WorldBuilder's `OpenGLGraphicsDevice`), post-scene Z-offset gated on `(Properties & 4) != 0 && (Properties & 8) == 0` per `GameSky::UpdatePosition` `0x00506dd0`. Sky-PES playback disabled by default (named-retail proves `GameSky` drops `pes_id`); `ACDREAM_ENABLE_SKY_PES=1` opens the experimental path. 1325 → 1331 tests. | Live ✓ |
+| N.1 | WorldBuilder-backed scenery (Chorizite/WorldBuilder fork as submodule, SceneryHelpers + TerrainUtils replace our inline ports) | Live ✓ |
 
 Plus polish that doesn't get its own phase number:
 - FlyCamera default speed lowered + Shift-to-boost
@@ -532,12 +533,16 @@ for our deletions/additions; merge upstream `master` periodically.
 **Sub-phases (strangler-fig with feature flags):**
 
 - **N.0 — Setup.** Submodule + project references + build green. ~1-2 hrs.
-- **N.1 — Scenery algorithm calls.** Replace `IsOnRoad` /
-  `DisplaceObject` / slope-normal calc / rotation / scale inside
-  `SceneryGenerator.Generate()` with calls to WB's `SceneryHelpers` +
-  `TerrainUtils`. Tiny adapter `LandBlock → TerrainEntry[]`. Keeps our
-  data flow + `ScenerySpawn` shape. Feature flag
-  `ACDREAM_USE_WB_SCENERY=1`. ~1-2 days.
+- **✓ SHIPPED — N.1 — Scenery algorithm calls.** Shipped 2026-05-08.
+  Replaced `IsOnRoad` / `DisplaceObject` / slope-normal calc / rotation /
+  scale inside `SceneryGenerator.Generate()` with calls to WB's
+  `SceneryHelpers` + `TerrainUtils`. Adapter `WbSceneryAdapter` produces
+  `TerrainEntry[]`. Visual verification at Holtburg confirmed Issue #49's
+  previously missing edge-vertex trees still visible after the migration;
+  rotation bug fixed (our retail port's `yawDeg = -(450-degrees)%360`
+  formula was ~180° off from retail's actual `Frame::set_heading` atan2
+  round-trip). One known cosmetic difference filed in ISSUES.md
+  (road-edge tree at landblock 0xA9B1).
 - **N.2 — Terrain math helpers.** Refactor `TerrainSurface.SampleZ` /
   `SampleNormal` / `SampleSurface` to call WB's `TerrainUtils.GetHeight`
   / `GetNormal` internally. ~1-2 days.