fix: alert title contrast, and make Storybook dev serve live library source

Two independent fixes:

1. Alert titles used text-<severity> directly on a bg-<severity>/15 tinted
   background. For danger (a very dark base hue) this reads as near-invisible
   text-on-tinted-background. The original PrimeVue-era Message design kept
   body/title text neutral and only accented the icon/left-border with the
   severity color -- restore that: alert text stays text-foreground, severity
   shows via a border-l-4 accent stripe instead of tinted text.

2. Root-caused why none of the last several fixes were showing up without a
   full `bun run build`: @nychthemeron/library's package.json exports its "."
   entry as ./dist/index.js unconditionally, and every story imports from the
   bare package specifier. So Storybook's dev server was always resolving to
   whatever the dist bundle looked like at last build time, never live
   source -- editing packages/library/src and restarting `bun run dev` (even
   with caches cleared) never picked up changes. Vite auto-injects a
   "development" resolution condition during `vite dev`/serve (and
   "production" during build), which is the standard fix for exactly this
   monorepo dev-vs-published split: added a "development" condition to the
   "." export pointing at src/index.ts, matching the pattern the "./components"
   sub-export already used. Also added the matching "@" alias to
   packages/playground/vite.config.ts, since resolving straight to library
   source pulls in its "@/lib/utils"-style internal imports, which playground's
   own Vite instance didn't previously know how to resolve.

   Verified both paths: dev server now reflects source edits without a
   library rebuild, and `bun run build` still produces a correct dist bundle
   with the same fix baked in.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packages/library/package.json

@@ -4,6 +4,7 @@
   "type": "module",
   "exports": {
     ".": {
+      "development": "./src/index.ts",
       "import": "./dist/index.js",
       "types": "./dist/src/index.d.ts"
     },

packages/library/src/components/ui/alert/index.ts

@@ -7,15 +7,15 @@ export { default as AlertDescription } from './AlertDescription.vue'
 export { default as AlertTitle } from './AlertTitle.vue'
 
 export const alertVariants = cva(
-  'relative grid w-full gap-1 rounded-lg border px-3 py-2.5 text-sm has-data-[slot=alert-action]:pr-10',
+  'relative grid w-full gap-1 rounded-lg border border-l-4 px-3 py-2.5 text-sm text-foreground has-data-[slot=alert-action]:pr-10',
   {
     variants: {
       variant: {
-        info: 'bg-info/15 border-info/30 text-foreground [&_[data-slot=alert-title]]:text-info',
-        success: 'bg-success/15 border-success/30 text-foreground [&_[data-slot=alert-title]]:text-success',
-        warning: 'bg-warning/15 border-warning/30 text-foreground [&_[data-slot=alert-title]]:text-warning',
-        danger: 'bg-destructive/15 border-destructive/30 text-foreground [&_[data-slot=alert-title]]:text-destructive',
-        secondary: 'bg-secondary/40 border-border text-foreground',
+        info: 'bg-info/15 border-info/30 border-l-info',
+        success: 'bg-success/15 border-success/30 border-l-success',
+        warning: 'bg-warning/15 border-warning/30 border-l-warning',
+        danger: 'bg-destructive/15 border-destructive/30 border-l-destructive',
+        secondary: 'bg-secondary/40 border-border',
       },
     },
     defaultVariants: {

packages/playground/vite.config.ts

@@ -8,6 +8,10 @@ export default defineConfig({
   resolve: {
     alias: {
       '~': fileURLToPath(new URL('./src', import.meta.url)),
+      // Matches packages/library's own alias -- needed because the "development"
+      // export condition on @nychthemeron/library resolves straight to that
+      // package's source (see its package.json), which itself imports via "@/...".
+      '@': fileURLToPath(new URL('../library/src', import.meta.url)),
     },
   },
 })