Reduce secret syncing to just .env

Strip hardcoded secrets from gitea/config/app.ini (already injected
via GITEA__ env vars) and commit it to git. Add download.sh to fetch
the act_runner binary on demand instead of syncing it. Everything else
(searxng settings, certbot certs, runner registration, Spotify tokens)
is generated at runtime.

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

gitea-runner/download.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+VERSION="0.2.11"
+BASE_URL="https://gitea.com/gitea/act_runner/releases/download/v${VERSION}"
+
+ARCH=$(uname -m)
+case "$ARCH" in
+    x86_64)  ASSET="act_runner-${VERSION}-linux-amd64" ;;
+    aarch64) ASSET="act_runner-${VERSION}-linux-arm64" ;;
+    armv7l)  ASSET="act_runner-${VERSION}-linux-armv7" ;;
+    *)
+        echo "Unsupported architecture: $ARCH" >&2
+        exit 1
+        ;;
+esac
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+DEST="${SCRIPT_DIR}/act_runner"
+
+echo "Downloading act_runner v${VERSION} for ${ARCH}..."
+curl -fSL "${BASE_URL}/${ASSET}" -o "$DEST"
+chmod +x "$DEST"
+echo "Downloaded to $DEST"