gitea-runner: fix log_info/warn/error writing to stdout, corrupting TEMPLATE

log_info() etc. wrote to stdout, unlike openbao's identical functions
which write to stderr specifically so $(fn) capture is safe. lib/common.sh's
detect_latest_alpine_template() does `log_info "Selected..."; echo "$tmpl"` —
in gitea-runner, TEMPLATE=$(detect_latest_alpine_template) therefore captured
the log line and ANSI codes along with the template name, breaking both the
pveam list lookup and pct create's template argument.

gitea-runner/install.sh

@@ -28,9 +28,10 @@ GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
 NC='\033[0m'
 
-log_info()  { echo -e "${GREEN}[INFO]${NC} $1"; }
-log_warn()  { echo -e "${YELLOW}[WARN]${NC} $1"; }
-log_error() { echo -e "${RED}[ERROR]${NC} $1"; }
+# Logs go to stderr so callers can safely use $(fn) without capturing log noise.
+log_info()  { echo -e "${GREEN}[INFO]${NC} $1" >&2; }
+log_warn()  { echo -e "${YELLOW}[WARN]${NC} $1" >&2; }
+log_error() { echo -e "${RED}[ERROR]${NC} $1" >&2; }
 
 require_root() {
   if [[ "$(id -u)" -ne 0 ]]; then