Update gitignore files for all components

Root: add OS/IDE/secrets patterns
webapp: add .vite/, .tsbuildinfo, .env.local
backend: add /createuser binary, bin/, uploads/ (submodule bump)
app: remove redundant entries, add *.hprof, *.class

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webapp/.gitignore

@@ -1,2 +1,9 @@
 node_modules/
 dist/
+.vite/
+*.tsbuildinfo
+
+# Environment
+.env
+.env.local
+.env.*.local