feat: add noisebell observability

remote/noisebell-common/src/lib.rs

@@ -12,6 +12,21 @@ pub fn validate_bearer(headers: &HeaderMap, expected: &str) -> bool {
         .unwrap_or(false)
 }
 
+pub fn prometheus_escape_label_value(value: &str) -> String {
+    let mut escaped = String::with_capacity(value.len());
+    for ch in value.chars() {
+        match ch {
+            '\\' => escaped.push_str("\\\\"),
+            '"' => escaped.push_str("\\\""),
+            '\n' => escaped.push_str("\\n"),
+            _ => escaped.push(ch),
+        }
+    }
+    escaped
+}
+
+pub const PROMETHEUS_CONTENT_TYPE: &str = "text/plain; version=0.0.4; charset=utf-8";
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum DoorStatus {