M0.5: detailed scenery, mountain/sea-cliff boundary, Godot 4.7

Scenery (all procedural, seeded, no imported assets):
- Terrain shader: grass/dry grass/dirt/sand/rock strata/snow + detail normals
- 5 tree types, faceted mossy rocks, cliff outcrops, sea stacks, bushes,
  logs and stumps, batched as MultiMesh per 48 m cell
- Wind-animated grass and flowers streamed in tiles around the player
- Lake (depth-shaded water with shore foam), ocean to the horizon,
  cloud sky shader, volumetric fog, glow, softer shadows
- Swimming: float at the surface, swim-jump to climb out

World bounds:
- Steep mountain rim with an invisible wall partway up; one side opens to
  a sheer sea cliff with the wall 1 m inside the edge; whole chunk is an
  island so the mesh edge is never visible
- Respawn safety net if the player leaves the walkable area or the map
- Fix: the cliff edge now tracks the wall in the headlands (it used to
  drop away inside the wall, leaving a pit with lake water hanging over it)

Tests: tests/test_boundary.gd (24-direction escape attempt) and
tests/test_terrain_edges.gd (no ground below waterline near the wall).

Upgrades the project to Godot 4.7 (project.godot rewritten by the 4.7
importer, .uid files added) and documents it in the setup guide.

docs/ROADMAP.md

@@ -7,13 +7,20 @@ actually run and see. Timelines assume solo dev + heavy AI assistance, steady
 ## M0 — World skeleton (single-player) · ~2–4 weeks
 **Goal:** walk around a lit, atmospheric terrain. Prove the look.
 - [x] Project scaffold, git repo, docs
-- [ ] Godot installed, project opens
-- [ ] First-person / third-person character controller (move, jump, mouse-look)
-- [ ] One flat/heightmap terrain chunk with a material
-- [ ] Atmospheric lighting: directional sun, sky, volumetric fog, tonemapping
-- [ ] Place one low-poly tree + rock to set the mood
+- [x] Godot installed, project opens
+- [x] First-person / third-person character controller (move, jump, mouse-look)
+- [x] One flat/heightmap terrain chunk with a material
+- [x] Atmospheric lighting: directional sun, sky, volumetric fog, tonemapping
+- [x] Place one low-poly tree + rock to set the mood
 - **Done when:** you load the game and walk around a Valheim-ish lit field.
 
+### M0.5 — Scenery & world bounds (done)
+- [x] Mountain-rim boundary (steep cliffs + invisible wall + respawn safety net),
+      covered by `tests/test_boundary.gd`
+- [x] Procedural terrain shader (grass/dirt/sand/rock strata/snow), lake + water shader
+- [x] 5 procedural tree types, faceted mossy rocks, cliff outcrops, bushes, logs, stumps
+- [x] Streamed wind-animated grass + flowers; cloud sky; swimming
+
 ## M1 — Survival loop (single-player) · ~3–5 weeks
 **Goal:** the core game verbs.
 - [ ] Resource nodes: chop tree → wood, mine rock → stone