WASM browser build: interned env keys, async kernel boot, bundled .sx platform

- Symbol interning in sx_types.ml: env lookups use int keys (intern/unintern)
  to avoid repeated string hashing in scope chain walks
- sx-platform.js: poll for SxKernel availability (WASM init is async)
- shell.sx: load sx_browser.bc.wasm.js when SX_USE_WASM=1
- bundle.sh: fix .sx file paths (web-signals.sx rename)
- browser/dune: target byte+js+wasm modes
- Bundle 23 .sx platform files for browser (dom, signals, router, boot, etc.)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hosts/ocaml/bin/mcp_tree.ml

@@ -709,6 +709,7 @@ let rec handle_tool name args =
     let selector = args |> member "selector" |> to_string_option in
     let expr = args |> member "expr" |> to_string_option in
     let actions = args |> member "actions" |> to_string_option in
+    let island = args |> member "island" |> to_string_option in
     (* Determine whether to run specs or the inspector *)
     let use_inspector = match mode with
       | Some m when m <> "run" -> true
@@ -745,6 +746,7 @@ let rec handle_tool name args =
         (match selector with Some s -> Some ("selector", `String s) | None -> None);
         (match expr with Some e -> Some ("expr", `String e) | None -> None);
         (match actions with Some a -> Some ("actions", `String a) | None -> None);
+        (match island with Some i -> Some ("island", `String i) | None -> None);
       ]) in
       let args_json = Yojson.Safe.to_string (Yojson.Safe.from_string (Yojson.Basic.to_string inspector_args)) in
       let cmd = Printf.sprintf "cd %s && node tests/playwright/sx-inspect.js '%s' 2>&1" project_dir (String.escaped args_json) in
@@ -1154,14 +1156,15 @@ let rec handle_tool name args =
        let bindings = ref [] in
        (* Walk env chain collecting all bindings *)
        let rec collect_bindings env acc =
-         Hashtbl.iter (fun k v ->
-           if not (Hashtbl.mem acc k) then Hashtbl.replace acc k v
+         Hashtbl.iter (fun id v ->
+           if not (Hashtbl.mem acc id) then Hashtbl.replace acc id v
          ) env.bindings;
          match env.parent with Some p -> collect_bindings p acc | None -> ()
        in
        let all = Hashtbl.create 256 in
        collect_bindings e all;
-       Hashtbl.iter (fun k v ->
+       Hashtbl.iter (fun id v ->
+         let k = Sx_types.unintern id in
          let kind = match v with
            | NativeFn _ -> "native"
            | Lambda _ -> "lambda"
@@ -1351,10 +1354,11 @@ let tool_definitions = `List [
      ("files", `Assoc [("type", `String "array"); ("items", `Assoc [("type", `String "string")]); ("description", `String "Multiple .sx files to load in order")]);
      ("setup", `Assoc [("type", `String "string"); ("description", `String "SX setup expression to run before main evaluation")])]
     ["expr"];
-  tool "sx_playwright" "Run Playwright browser tests or inspect SX pages interactively. Modes: run (spec files), inspect (page report), diff (SSR vs hydrated), eval (JS expression), interact (action sequence), screenshot."
+  tool "sx_playwright" "Run Playwright browser tests or inspect SX pages interactively. Modes: run (spec files), inspect (page/island report with leak detection and handler audit), diff (full SSR vs hydrated DOM), hydrate (lake-focused SSR vs hydrated comparison — detects clobbering), eval (JS expression), interact (action sequence), screenshot."
     [("spec", `Assoc [("type", `String "string"); ("description", `String "Spec file to run (run mode). e.g. stepper.spec.js")]);
-     ("mode", `Assoc [("type", `String "string"); ("description", `String "Mode: run, inspect, diff, eval, interact, screenshot")]);
+     ("mode", `Assoc [("type", `String "string"); ("description", `String "Mode: run, inspect, diff, hydrate, eval, interact, screenshot")]);
      ("url", `Assoc [("type", `String "string"); ("description", `String "URL path to navigate to (default: /)")]);
+     ("island", `Assoc [("type", `String "string"); ("description", `String "Filter inspect to a specific island by name (e.g. home/stepper)")]);
      ("selector", `Assoc [("type", `String "string"); ("description", `String "CSS selector to focus on (screenshot mode)")]);
      ("expr", `Assoc [("type", `String "string"); ("description", `String "JS expression to evaluate (eval mode)")]);
      ("actions", `Assoc [("type", `String "string"); ("description", `String "Semicolon-separated action sequence (interact mode). Actions: click:sel, fill:sel:val, wait:ms, text:sel, html:sel, attrs:sel, screenshot, screenshot:sel, count:sel, visible:sel")])]