Update ARCHITECTURE.md and CLAUDE.md for new module structure

Documents render.rs, editor.rs, and glyph_picker.rs; updates the module
structure diagram and main.rs section to reflect the refactored layout.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -50,17 +50,27 @@ The game is a single Rust binary using **eframe 0.33 / egui 0.33** for the GUI.
 - `impl From<MapFile> for Board` — converts a parsed file into a ready-to-use `Board`
 - `pub fn load(path: &str) -> Result<Board, Box<dyn std::error::Error>>` — reads and converts a `.toml` map file
 
-**`src/main.rs`** — app entry point:
+**`src/main.rs`** — app entry point and frame loop:
 - `AppMode` enum (`Play` | `Edit`) — gates arrow-key input; toggles the side panel and viewport mode
-- `EditorTab` enum (`Palette` | `Board` | `World`) — which tab is active in the side panel
-- `EditorState` — holds `selected: Archetype`, `glyph: Glyph` (the glyph to stamp, independent of archetype default), `glyph_picker_open: bool`, and `tab: EditorTab`. Selecting a new archetype resets `glyph` to that archetype's default.
-- Window uses fixed default size (`DEFAULT_WINDOW_W = 840`, `DEFAULT_WINDOW_H = 524`) independent of map dimensions; `board_origin()` handles centering or player-centered scrolling at runtime
-- `draw_glyph(painter, origin, x, y, glyph)` draws one cell: filled rect (bg) + monospace char (fg)
-- `board_origin(available, board_w, board_h, player)` — if the board fits in the viewport, centers it; if it overflows, centers on the player and clamps to board edges (no empty space shown)
-- Player is rendered on top of the board using `Glyph::player()`
-- **Play mode**: arrow keys move player; viewport scrolls to keep player centered when map > window
-- **Edit mode**: `ScrollArea::both()` wraps the board so scroll bars appear when map > window; click-to-paint stamps `(self.editor.glyph, self.editor.selected)` at the clicked cell; side panel (200 px, resizable) shows Palette/Board/World tabs
-- **Glyph picker dialog** (`egui::Window`): opened from the Palette tab; shows a board-palette of unique glyphs, fg/bg `color_edit_button_srgba` pickers, and a 16×6 grid of printable ASCII chars (0x20–0x7E)
+- `App` holds `GameState`, `AppMode`, and `EditorState`; `update` phases: input → menu bar → editor panel → board → glyph picker dialog
+- **Play mode**: arrow keys move player; `render::board_origin` centers or player-tracks the viewport
+- **Edit mode**: `ScrollArea::both()` wraps the board; click-to-paint stamps `(editor.glyph, editor.selected)`; calls `editor::show_editor_panel` and `glyph_picker::show`
+
+**`src/render.rs`** — cell rendering constants and drawing primitives:
+- `CELL_W = 14.0`, `CELL_H = 20.0` and window sizing constants (`DEFAULT_WINDOW_W = 840`, `DEFAULT_WINDOW_H = 524`)
+- `draw_glyph(painter, origin, x, y, glyph)` — filled rect (bg) + centered monospace char (fg)
+- `draw_board(painter, origin, board)` — draws all cells then player overlay
+- `board_origin(available, board_w, board_h, player)` — centers board or clamps to player with no empty space
+- `pos_to_cell(origin, pos) -> (i32, i32)` — pixel → cell coordinates via floor division; negatives signal out-of-bounds
+
+**`src/editor.rs`** — editor state and side panel:
+- `EditorTab` enum (`Palette` | `Board` | `World`) — which tab is active
+- `EditorState` — holds `selected: Archetype`, `glyph: Glyph`, `glyph_picker_open: bool`, `tab: EditorTab`; selecting a new archetype resets `glyph` to that archetype's default
+- `show_editor_panel(ctx, editor, board)` — resizable right-side panel (default 200 px); Palette tab shows archetype list and glyph preview button; Board/World tabs are placeholders
+
+**`src/glyph_picker.rs`** — floating glyph picker dialog:
+- `show(ctx, open, glyph, board_cells)` — takes `open: &mut bool` and `glyph: &mut Glyph` directly; no dependency on `EditorState`
+- Three sections: board palette (unique glyphs, click to select), FG/BG color pickers, 16×6 printable ASCII character grid
 
 ### Map file format (`maps/*.toml`)