fix(webapp): preserve Vite source maps for library files without @/ imports

The apollon-alias-resolver load hook rewrites the library's `@/` imports (which
collide with the webapp's own `@/`). It previously intercepted every file under
library/ and returned `map: null`, discarding source maps for all of them. It
now only intercepts files that actually rewrite a `@/…` import; every other
library file falls through to Vite's native loader and keeps its source map (and
Fast Refresh). The rewrite logic is unchanged.

Verified: webapp build resolves `@/` (0 raw `@/` left, rewritten to absolute
paths), and a non-`@/` library component is served with both a source map and
React Fast Refresh.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: FelixTJDietrich

standalone/webapp/vite.config.ts

@@ -24,32 +24,36 @@ const apollonAliases = [
 ]
 
 // The editor library uses a `@/` alias -> library/lib, which collides with the
-// webapp's own `@/` -> src. Rewrite `@/…` to an absolute library/lib path only
-// inside files under the library directory; the webapp's `@/` keeps mapping to src.
+// webapp's own `@/` -> src. Rewrite `@/…` imports in library files to an absolute
+// library/lib path (the webapp's `@/` keeps mapping to src). Only files that
+// actually import `@/…` are intercepted, so every other library file keeps Vite's
+// native source maps; the rewrite is line-preserving, so only the import lines of
+// the rewritten files shift.
 const apollonAliasResolver = {
   name: "apollon-alias-resolver",
   enforce: "pre" as const,
   async load(id: string) {
     const libraryRoot = resolve(__dirname, "../../library").replace(/\\/g, "/")
     if (!id.replace(/\\/g, "/").includes(libraryRoot)) return null
+    let original: string
     try {
-      let code = await fs.promises.readFile(id, "utf-8")
-      const libRoot = resolve(__dirname, "../../library/lib").replace(
-        /\\/g,
-        "/"
-      )
-      code = code.replace(
+      original = await fs.promises.readFile(id, "utf-8")
+    } catch {
+      return null
+    }
+    if (!original.includes("@/")) return null
+    const libRoot = resolve(__dirname, "../../library/lib").replace(/\\/g, "/")
+    const code = original
+      .replace(
         /from\s+["']@\/([^"']+)["']/g,
         (_m, p) => `from "${resolve(libRoot, p).replace(/\\/g, "/")}"`
       )
-      code = code.replace(
+      .replace(
         /import\s+["']@\/([^"']+)["']/g,
         (_m, p) => `import "${resolve(libRoot, p).replace(/\\/g, "/")}"`
       )
-      return { code, map: null }
-    } catch {
-      return null
-    }
+    if (code === original) return null
+    return { code, map: null }
   },
 }