feat: add custom HMR FS icon loader - #439

This PR introduces a new filesystem-backed custom collection loader that can participate in HMR by tracking resolved SVG paths and invalidating the corresponding ~icons/... virtual modules across supported bundlers.

Changes:

• Added FileSystemHMRIconLoader (and supporting HMR plumbing) to enable HMR for filesystem custom collections.
• Updated the unplugin entry to register watched SVG files (non-Vite) and to invalidate Vite modules via handleHotUpdate.
• Updated multiple examples (Vite, Webpack, Rspack, Nuxt) to demonstrate the new loader.

• Files reviewed: 14/18 changed files
• Comments generated: 5
• Review effort level: Lite

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

src/loaders.ts:70

• resolveIcon() uses fs.lstat(). For symlinked SVGs, lstat().isFile() is false, so icons behind symlinks will never load. Using fs.stat() (follows symlinks) avoids this class of false negatives while still letting you check isFile().

src/types.ts:12

• CustomHMRIconLoader is now part of the public types and FileSystemHMRIconLoader() returns it, but Options.customCollections is still typed as Record<string, CustomIconLoader | InlineCollection>. This makes TypeScript configs unable to pass ...FileSystemHMRIconLoader(...) without casts, even though runtime support exists in resolveOptions().

export interface CustomHMRIconLoader {
  /**
   * The name of the custom collection.
   */
  name: string

• Files reviewed: 14/18 changed files
• Comments generated: 3
• Review effort level: Lite

Suppressed comments (2)

Previously missed (2) — in code that hasn't changed since the last review.

src/loaders.ts:74

• Using fs.lstat() here prevents loading icons that are symlinked (common in monorepos/workspaces), because lstat().isFile() is false for symbolic links. fs.stat() follows symlinks and keeps the behavior closer to typical file loaders while still ensuring the target is a file.
  src/loaders.ts:76
• pathToName stores only one icon name per SVG path. If the same file is resolved through different name variants (e.g. SteeringWheel.svg imported as both SteeringWheel and steering-wheel), the later import overwrites the mapping and HMR invalidation will only refresh one of the virtual ids. To make HMR reliable, consider tracking a set/list of icon names per path and invalidating all matching virtual modules.

• Files reviewed: 14/18 changed files
• Comments generated: 1
• Review effort level: Lite