feat(gitea): add Umami analytics via custom header template

Injects the Umami tracking script into every Gitea page using a custom
header.tmpl generated at startup via envsubst. Script URL and website ID
are externalized to UMAMI_SCRIPT_URL / UMAMI_WEBSITE_ID env vars.

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

gitea/.env.example

@@ -1,3 +1,5 @@
 TRAEFIK_HOST=dev.example.com
 NETWORK_NAME=falcon_network
 RUNNER_TOKEN=change_me
+UMAMI_SCRIPT_URL=https://umami.example.com/script.js
+UMAMI_WEBSITE_ID=change_me

gitea/compose.yml

@@ -2,6 +2,13 @@ services:
   gitea:
     image: gitea/gitea:latest
     container_name: gitea
+    entrypoint:
+      - /bin/sh
+      - -c
+      - |
+        mkdir -p /data/gitea/templates/custom
+        envsubst '$UMAMI_SCRIPT_URL $UMAMI_WEBSITE_ID' < /etc/gitea-umami/custom/header.tmpl.tpl > /data/gitea/templates/custom/header.tmpl
+        exec /usr/bin/entrypoint
     environment:
       TZ: ${TIMEZONE:-Europe/Amsterdam}
       USER_UID: 1000
@@ -34,6 +41,8 @@ services:
       GITEA__ui__THEMES: gitea-auto,gitea-light,gitea-dark,arc-green,edge-auto,edge-dark,edge-light,everforest-auto,everforest-dark,everforest-light,gruvbox-auto,gruvbox-dark,gruvbox-light,gruvbox-material-auto,gruvbox-material-dark,gruvbox-material-light,nord,palenight,soft-era,sonokai,sonokai-andromeda,sonokai-atlantis,sonokai-espresso,sonokai-maia,sonokai-shusia
       GITEA__ui__DEFAULT_THEME: nord
       GITEA__ui__ENABLE_FEED: "true"
+      UMAMI_SCRIPT_URL: ${UMAMI_SCRIPT_URL}
+      UMAMI_WEBSITE_ID: ${UMAMI_WEBSITE_ID}
     ports:
       - "2222:2222"
     volumes:
@@ -41,6 +50,7 @@ services:
       - ../.data/gitea/config:/etc/gitea
       - ./css:/data/gitea/public/assets/css:ro
       - ./img:/data/gitea/public/assets/img:ro
+      - ./templates:/etc/gitea-umami:ro
       - /etc/localtime:/etc/localtime:ro
     depends_on:
       db:

gitea/templates/custom/header.tmpl.tpl

@@ -0,0 +1 @@
+<script defer src="${UMAMI_SCRIPT_URL}" data-website-id="${UMAMI_WEBSITE_ID}"></script>