feat: allow dev server to run without building kumo first

[danielrobertson]

Summary

• Fix dev server startup to not require pnpm --filter @cloudflare/kumo build first
• Add missing HMR alias for @cloudflare/kumo/code export

Problem

Running pnpm dev on a fresh clone (or after rm -rf packages/kumo/dist) failed with:

Cannot find module '@cloudflare/kumo/scripts/theme-generator/config'

This happened because vite-plugin-kumo-colors.ts imported from the package path, which resolves via package.json exports to
dist/scripts/theme-generator/config.js—a file that doesn't exist until the kumo package is built.

Additionally, after fixing that, another error appeared for @cloudflare/kumo/code which was missing from the HMR plugin's alias list.

Solution

1. Changed vite-plugin-kumo-colors.ts to import directly from the relative source path (../../../kumo/scripts/theme-generator/config.js) instead of the
   package export. This matches the pattern already used elsewhere in the file (line 102-105 already referenced this path for file watching).
2. Added @cloudflare/kumo/code and @cloudflare/kumo/code/server to the HMR plugin's resolve aliases.

Test plan

• Delete packages/kumo/dist directory
• Run pnpm install && pnpm dev
• Verify dev server starts without errors
• Verify docs site loads correctly at localhost:4321

[stritt]

@danielrobertson are you still working on this?