Clean up project inconsistencies and unused dependencies

Fix license field to match LICENSE file, remove Astro artifacts from previous migration, and remove unused marked dependency.

Changes:
- Update package.json license from ISC to MIT
- Remove .astro directory and .gitignore reference
- Remove unused marked dependency from package.json
- Update pnpm-lock.yaml accordingly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: stared

.gitignore

@@ -3,7 +3,6 @@ node_modules/
 
 # Build outputs
 dist/
-.astro/
 *.local
 
 # Editor directories and files

package.json

@@ -16,7 +16,7 @@
     "physics"
   ],
   "author": "",
-  "license": "ISC",
+  "license": "MIT",
   "packageManager": "pnpm@10.19.0",
   "devDependencies": {
     "@types/node": "^24.9.2",
@@ -27,7 +27,6 @@
     "vite": "^7.1.12"
   },
   "dependencies": {
-    "katex": "^0.16.25",
-    "marked": "^16.4.1"
+    "katex": "^0.16.25"
   }
 }