feat(themes,templates,signup-gate): add signup gate, remove custom theme switcher from links footer

signup-gate/.env.example

@@ -0,0 +1,13 @@
+GITEA__URL=https://git.kotikot.com
+GITEA__TOKEN=<admin token with write:admin scope>
+GITEA__SITE_NAME=KOTIKOT Git
+
+APP__PORT=8002
+
+GATE__CHALLENGE_TTL=900
+GATE__MIN_SOLVE_SECONDS=1.5
+GATE__MAX_ACCOUNT_AGE_DAYS=30
+
+LOG__LEVEL=INFO
+LOG__SHOW_TIME=false
+LOG__CONSOLE_WIDTH=150