feat: initial commit - complete website monitoring application

Build a comprehensive website monitoring application with ReasonML, OCaml, and server-reason-react.

Features:
- Real-time website monitoring with HTTP status checks
- Email and webhook alerting system
- Beautiful admin dashboard with Tailwind CSS
- Complete REST API for CRUD operations
- Background monitoring scheduler
- Multi-container Docker setup with 1-core CPU constraint
- PostgreSQL database with Caqti
- Full documentation and setup guides

Tech Stack:
- OCaml 5.0+ with ReasonML
- Dream web framework
- server-reason-react for UI
- PostgreSQL 16 database
- Docker & Docker Compose

Files:
- 9 OCaml source files (1961 LOC)
- 6 documentation files (1603 LOC)
- Complete Docker configuration
- Comprehensive API documentation

💘 Generated with Crush

lib/monitor.ml

@@ -0,0 +1,158 @@
+(* Website monitoring logic *)
+
+open Lwt.Infix
+open Cohttp
+open Cohttp_lwt_unix
+open Database
+
+(* Result of a website check *)
+type check_result = {
+  status_code: int;
+  response_time: float; (* milliseconds *)
+  error_message: string option;
+  is_success: bool;
+}
+
+(* Check a single website *)
+let check_website (website : Website.t) : check_result Lwt.t =
+  let start_time = Unix.gettimeofday () in
+
+  let uri =
+    try Uri.of_string website.url
+    with _ -> failwith (Printf.sprintf "Invalid URL: %s" website.url)
+  in
+
+  (* Create HTTP client with timeout *)
+  let timeout = website.timeout in
+  let client = Client.conns ~connection_timeout:(float_of_int timeout) () in
+
+  (* Make HTTP request *)
+  Client.get ~uri client
+  >>= fun (response, body) ->
+  let end_time = Unix.gettimeofday () in
+  let response_time = (end_time -. start_time) *. 1000.0 in
+
+  let status_code = Code.code_of_status (Cohttp.Response.status response) in
+
+  let is_success =
+    status_code = website.expected_status && Code.is_success status_code
+  in
+
+  let result = {
+    status_code;
+    response_time;
+    error_message = None;
+    is_success;
+  } in
+
+  (* Drain body to complete request *)
+  Cohttp_lwt.Body.to_string body
+  >>= fun _body ->
+  Lwt.return result
+  |> Lwt.catch
+    (fun exn ->
+      let error_message = Some (Printexc.to_string exn) in
+      let result = {
+        status_code = 0;
+        response_time = (Unix.gettimeofday () -. start_time) *. 1000.0;
+        error_message;
+        is_success = false;
+      } in
+      Lwt.return result)
+
+(* Check website and store result *)
+let check_and_store_website (website : Website.t) : unit Lwt.t =
+  Logs.app (fun m ->
+    m "Checking website: %s (%s)" website.name website.url);
+
+  check_website website
+  >>= fun result ->
+  let now = Ptime.v (Unix.gettimeofday ()) in
+
+  (* Store check history *)
+  let error_message =
+    match result.error_message with
+    | None -> None
+    | Some msg -> Some msg
+  in
+
+  CheckHistories.create website.id result.status_code result.response_time error_message
+  >>= fun () ->
+
+  (* Update website status *)
+  let last_status = Some result.status_code in
+  let last_checked = now in
+
+  Websites.update_status website.id last_checked last_status
+  >>= fun () ->
+
+  Logs.app (fun m ->
+    m "Website %s check result: status=%d, time=%.2fms, success=%b"
+      website.name result.status_code result.response_time result.is_success);
+
+  (* Trigger alerts if needed *)
+  Alert.trigger_alerts website result
+  >>= fun () ->
+  Lwt.return_unit
+  |> Lwt.catch
+    (fun exn ->
+      Logs.err (fun m ->
+        m "Error checking website %s: %s" website.name (Printexc.to_string exn));
+      Lwt.return_unit)
+
+(* Check all active websites *)
+let check_all_active_websites () : unit Lwt.t =
+  Websites.get_active ()
+  >>= fun websites ->
+  Lwt_list.iter_p check_and_store_website websites
+  >>= fun () ->
+  Logs.app (fun m -> m "Completed checking all active websites");
+  Lwt.return_unit
+
+(* Get current status summary for a website *)
+let get_website_status (website_id : int64) : Yojson.Basic.t Lwt.t =
+  Websites.get_by_id website_id
+  >>= function
+  | None -> Lwt.return Yojson.Basic.(`Null)
+  | Some website ->
+      CheckHistories.get_by_website_id website_id 10
+      >>= fun histories ->
+      let recent_checks =
+        List.map
+          (fun (h : CheckHistory.t) ->
+            Yojson.Basic.(
+              `Assoc
+                [
+                  ("id", `String (Int64.to_string h.id));
+                  ("status_code", `Int h.status_code);
+                  ("response_time", `Float h.response_time);
+                  ("error_message",
+                   (match h.error_message with
+                    | None -> `Null
+                    | Some msg -> `String msg));
+                  ("checked_at", `String (Ptime.to_rfc3339 h.checked_at));
+                ]))
+          histories
+      in
+
+      let website_json =
+        Yojson.Basic.(
+          `Assoc
+            [
+              ("id", `String (Int64.to_string website.id));
+              ("name", `String website.name);
+              ("url", `String website.url);
+              ("expected_status", `Int website.expected_status);
+              ("active", `Bool website.active);
+              ("last_checked",
+               (match website.last_checked with
+                | None -> `Null
+                | Some t -> `String (Ptime.to_rfc3339 t)));
+              ("last_status",
+               (match website.last_status with
+                | None -> `Null
+                | Some s -> `Int s));
+              ("recent_checks", `List recent_checks);
+            ])
+      in
+      Lwt.return website_json