perf: reduce bundle size by 34% (35MB → 23MB)

[sorrycc]

Summary

• Deduplicate shiki via resolve.dedupe: ["shiki"] in electron-vite config — @pierre/diffs (shiki@3) and the app (shiki@4) were each bundling their own copy of all 230+ language grammars and 65+ themes, producing 232 byte-identical duplicate chunks. This eliminates ~9 MB of JS.
• Resize PNG app icons from 1024–1646px originals down to 64×64 — these icons render at size-4 (16×16 CSS / 32×32 Retina), so 64px provides 4× coverage. Saves ~1.7 MB.

Metric	Before	After	Change
Total dist	35 MB	23 MB	-12 MB (-34%)
JS files	696	393	-303 files
JS total	29.3 MB	20.3 MB	-9 MB (-31%)
PNG icons	1.8 MB	48 KB	-1.7 MB (-97%)
Duplicate chunks	232	3	-229

Test plan

• bun ready passes (format + typecheck + lint + 261 tests)
• Verify app icons render correctly in the "Open in" dropdown
• Verify code highlighting works in chat messages (shiki)
• Verify diff viewer works (MultiFileDiff / @pierre/diffs)
• Verify mermaid diagrams render in markdown

[github-actions]

Build Ready

Architecture	Download	Size
Apple Silicon	Download	187.46 MB
Intel	Download	195.14 MB