feat: replace 2× supersampling with 1× bitmap fonts and explicit dithering

[ghcpuman902]

Summary

This PR replaces the old 2× supersampling + blanket dither/heuristic pipeline with 1× rendering and targeted crispness tools: traced bitmap fonts for text, palette-aware photo dithering at data-fetch time, and opt-in Floyd-Steinberg only where a recipe explicitly asks for it.

Render pipeline change (important)

Before (on main):

• Recipes like hacker-news, calendar, simple-text, and wikipedia set renderSettings: { supersample: true }.
• getRenderScale() (lib/recipes/render/settings.ts) rendered Takumi/Satori output at 2× device resolution, then downscaled with sharp back to physical pixels.
• The legacy BMP path defaulted to Floyd-Steinberg + edge-snap (applyEdgeSnap ?? true) as a global sharpness hack.
• This was never wired per-recipe in a meaningful way — it was a blanket workaround for soft vector text on e-ink.

After (this PR):

• Always render at 1× physical resolution. supersample and lib/recipes/render/settings.ts are removed.
• BMP edge-snap defaults to off (applyEdgeSnap ?? false).
• Crispness is handled explicitly instead of via supersampling:
  1. Bitmap fonts — baseline-relative v2 format, tracing pipeline, BitmapText, and packs (Block Kie, Geist Pixel Grid/Square, Geneva, Pixelify Sans) for pixel-aligned text at native resolution.
  2. Recipe prepareForDevice — album and wikipedia pre-dither embedded photos with palette-aware white-noise dithering (ditherImageToDataUrl) before JSX render, using the device’s gray levels.
  3. Opt-in device dither — renderSettings.dither: true enables Floyd-Steinberg during palette quantization in renderDeviceImage (default off). No recipe sets this yet; photos use prepareForDevice instead.

Expected visual change: Photo recipes (album, wikipedia thumbnails) should improve. Text-heavy recipes still on Takumi/Satori vector fonts (hacker-news, calendar, local-news, wikipedia body) may look softer until migrated to BitmapText — that is intentional; 2× downscale was masking the problem rather than fixing it.

Also includes: bitmap font designer overhaul, /api/bitmap-fonts/[packId], album city presets, TRMNL MAC setup fix, shared formatErrorMessage, README local-setup notes, and docs/pixel-font.md spec.

Test plan

• pnpm lint
• pnpm typecheck
• pnpm test (105 tests)
• pnpm build
• Compare device preview before/after on a recipe that previously used supersample: true (e.g. hacker-news, simple-text) — expect softer vector text until bitmap font migration
• Album / wikipedia — verify dithered photos on 1-bit and multi-gray palettes
• Bitmap font designer: edit glyph, preview paragraph layout, export pack
• BitmapText on simple-text / device preview — baseline alignment
• pnpm run generate:fonts
• Device setup MAC recognition on real TRMNL hardware

Follow-up

• Migrate remaining vector-font recipes (wikipedia, hacker-news, calendar, local-news) to traced BitmapText packs for fully crisp 1× text.
• Coordinate with open PR Fix/remove grayscale parameter #78 (fix/remove-grayscale-parameter) if both touch the render/device path.

[ghcpuman902]

Render pipeline — commit trail

For reviewers tracing the 2× removal vs new dithering:

Commit	What changed
6794844	Removes 2× supersampling: deletes lib/recipes/render/settings.ts, drops supersample: true from recipe meta, renders at 1× in rasterize.ts (no sharp downscale), flips BMP applyEdgeSnap default to false, wires opt-in renderSettings.dither into renderDeviceImage.
7fbadfb	Adds explicit photo dithering: ditherImageToDataUrl + prepareForDevice hook on album/wikipedia; white-noise dither tuned to palette gray levels (getPaletteGrayLevels). This replaces the old “dither everything at BMP export” approach for embedded images.
37e98f0+	Bitmap font path for crisp 1× text (designer, packs, BitmapText, weather BitmapMarker).

What was removed (the old blanket pipeline):

// lib/recipes/render/settings.ts (deleted)
export const SUPERSAMPLE_SCALE = 2;
// recipes: renderSettings: { supersample: true }
// rasterize: render 2× → sharp.resize(1×) → BMP with edge-snap

What replaced it:

• Text → pixel font packs at 1× (not downscaled vector)
• Photos → prepareForDevice dithers source images before they enter JSX
• Full-frame palette quantization → Floyd-Steinberg only when renderSettings.dither: true (currently unused; default off)

Release: merge to main → release workflow auto-bumps patch, tags v*.*.*, publishes GitHub Release + Docker. No version change in this branch; do not [skip release] unless intentionally holding back a user-visible release.

[rbouteiller]

It seems we have some scripts repeated in scripts/lib and lib/bitmap-font, maybe we want an unified surface

[rbouteiller]

This file seems not needed and not referenced in the code, should we delete it ?

[rbouteiller]

SHould we commit generated files ? Or have a generation step in readme ?