Move executables to build/ dir

.gitignore

@@ -1,3 +1,3 @@
 .env
 users.yaml
-substr
+build/

deno.json

@@ -2,7 +2,7 @@
   "tasks": {
     "dev": "deno run --allow-all --watch server.ts",
     "server": "deno run --allow-all server.ts",
-    "compile": "deno compile --allow-all --include ./assets/ --output substr server.ts",
+    "compile": "deno compile --allow-all --include ./assets/ --output ./build/substr_x86_64-unknown-linux-gnu server.ts",
     "test": "deno test --allow-read --allow-env"
   },
   "imports": {