refactor(server): use type guard to eliminate as Target casts in compile.ts

apps/server/compile.ts

@@ -4,14 +4,17 @@ import process from 'node:process'
 const ENTRYPOINT = '.output/server/index.mjs'
 const OUTDIR = 'out'
 
-const VALID_TARGETS = [
-  'bun-windows-x64',
-  'bun-darwin-arm64',
-  'bun-linux-x64',
-  'bun-linux-arm64',
-] as const
+const TARGETS = {
+  'bun-windows-x64': true,
+  'bun-darwin-arm64': true,
+  'bun-linux-x64': true,
+  'bun-linux-arm64': true,
+} as const
 
-type Target = (typeof VALID_TARGETS)[number]
+type Target = keyof typeof TARGETS
+
+const isTarget = (value: unknown): value is Target =>
+  typeof value === 'string' && value in TARGETS
 
 const HOST_MAP: Record<string, Target> = {
   'win32-x64': 'bun-windows-x64',
@@ -24,12 +27,12 @@ const resolveTarget = (): Target => {
   const idx = process.argv.indexOf('--target')
   if (idx !== -1) {
     const value = process.argv[idx + 1]
-    if (!value || !VALID_TARGETS.includes(value as Target)) {
+    if (!isTarget(value)) {
       throw new Error(
-        `Invalid target: ${value}\nAllowed: ${VALID_TARGETS.join(', ')}`,
+        `Invalid target: ${value}\nAllowed: ${Object.keys(TARGETS).join(', ')}`,
       )
     }
-    return value as Target
+    return value
   }
 
   const key = `${process.platform}-${process.arch}`