Convert all VisualShaders to plain Shaders; clean editor noise

Godot 4 emits two unavoidable warnings every time it reconstructs a
Godot-3-authored VisualShader graph: 'graph_offset property is
deprecated' (the editor's pan position, removed in 4.x) and
'connect_nodes_forced: Index p_from_port = 1 is out of bounds'
(node-graph ports that no longer line up). The compiled GLSL inside
each ShaderMaterial is correct; only the graph reconstruction is
broken.

scripts/devisualize_shaders.gd walks every .material, .tres, and
.mesh under res:// and replaces ShaderMaterial.shader from
VisualShader to a plain Shader carrying the same .code. 15 materials
converted (font outline, dissolve, color tints, book/candle/godet/
growler/parchment/rock-floor/stool/table). Godot now loads the
compiled shader directly with no graph reconstruction → both
warnings gone, rendering identical.

Also:
- scripts/resave_scenes.gd: load + re-save every .tscn so inline
  ArrayMesh sub-resources (notably WarCraft.tscn::17, the baked
  floor) move from Godot-3 PoolByteArray to Godot-4 PackedByteArray
  surface format. Silences 'Mesh uses old surface format'.
- scripts/find_visualshaders.gd: companion audit tool that lists
  every Resource still backed by a VisualShader. Useful if new
  legacy materials get added.
- Drop the now-orphan inline VisualShader / ShaderMaterial sub-
  resources (id 1..17) from Summary.tscn. The PanelWood lost its
  screen-blend tint material; a plain Panel renders fine and the
  effect can be re-authored as a hand-written shader if wanted.
- Add releases/.gdignore and tighten .gitignore so Godot stops
  warning 'Detected another project.godot at res://releases'. The
  releases/ directory has its own placeholder project.godot which
  Godot would otherwise flag at every editor open.

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

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