feat(watch): live-reload theme and chrome on config change

[eduwass]

Summary

When running hunk diff --watch, the viewer now live-reloads its theme and chrome the moment Hunk's config changes — no restart required. Previously --watch only tracked the diff input, so editing ~/.config/hunk/config.toml (e.g. switching a [custom_theme] palette from a theming tool) had no effect until you quit and relaunched.

What this adds

The watch loop now also watches Hunk's config files and reloads on change:

• The global config (~/.config/hunk/config.toml) and the repo-local config (.hunk/config.toml) are folded into the existing diff-input watch poll via a new computeConfigSignature() in core/watch.ts.
• Keeping it in the same poll loop means there's a single in-flight guard, so a config reload can never race the diff reload.
• On any change (input or config) it reuses refreshCurrentInput(), which re-runs the normal config resolution pipeline — so freshly-read [custom_theme] / [custom_theme.syntax] palettes repaint live — while preserving the active view options and any CLI overrides (no --theme/--mode flag gets silently clobbered by config).

Only active in --watch mode, so default one-shot reviews are unchanged.

Testing

• bun run format:check
• bun run lint
• bun run typecheck
• bun run test:theme-contrast
• bun test src/core/watch.test.ts — added unit coverage for computeConfigSignature (missing global config, change detection, repo-local .hunk/config.toml pickup)
• Real render smoke test: ran hunk diff --watch against a repo, switched the active theme so a tool rewrote [custom_theme], and confirmed the running viewer repainted from a dark to a light palette (background #2D2B55 → #f9f9f9, panels and diff bands updated) without a restart, and back again.

[greptile-apps]

PR author is not in the allowed authors list.

[benvinegar]

I wonder if it should just do this always? Vs --watch

Precedent seems to be VS Code, Cursor, etc. Those all basically apply their settings immediately, right?

[eduwass]

Hey @benvinegar yeah good point. VSCode/Cursor would update automatically, probably what we'd want here too.

[eduwass]

@benvinegar made it always-on now, no --watch required. The viewer always polls the config files (global + repo-local) and live-reloads theme/chrome on change, the way VS Code / Cursor apply settings on save.