Reorganize assets; switch the HUD to the Micro Chat font

Source packs move to assets/packs (untouched), maps to assets/maps, and the
palette/sketch leftovers from the 8-bit era go. tools/mkfont.py repacks
VEXED's Micro Chat sheet (8-column grid, 8x10 cells) into the CP437 atlas
layout the font loader already reads, cropped to 8x9 so the HUD can use an
8 px line height. The CGA atlas is dropped in its favor.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

notes/07-map-loader.md

@@ -13,7 +13,7 @@ TMX/XML. No header, no dimensions. The loader derives them from the content:
 - **width** = number of fields in the first row
 - **height** = number of rows
 
-The current test map lives at `assets/map_test` (30×30, tile ids 25 / 74 / 75 / 146).
+The current test map lives at `assets/maps/map_test` (30×30, tile ids 25 / 74 / 75 / 146).
 A trailing comma per row is tolerated; ragged rows panic (they indicate a corrupt export).
 
 ---
@@ -62,7 +62,7 @@ No `firstgid` subtraction: the authored ids already line up with `overworld.png`
 array is also the natural on-disk layout should chunks ever be streamed from disk (RLE over
 the `u16`s would do) — the CSV stays the interchange format for external tooling. The map's
 top-left tile sits at world (0, 0). Loading a 256×256 map takes well under a millisecond in
-release; the map path is the game's first CLI argument (`game assets/map_large`).
+release; the map path is the game's first CLI argument (`game assets/maps/map_large`).
 
 **Edge border:** a 30×30 map only fills part of chunk (0,0) (which spans tiles 0–31). Tiles
 inside a loaded chunk but outside the authored map are emitted as an *invisible solid border*