Uncap watershed detail in the Node binding + sync docs

`6f163fc` widened watershed_detail from u8 to u32 in the core, CLI, and
Python binding but not the Node/wasm binding, which still assigned a u8 to
config.watershed_detail — a wasm build error (E0308). Widen the Node
Options field to u32 and refresh every "0..=255" watershed doc (CLI help,
Config field, .pyi, index.d.ts, and all three READMEs) to reflect that the
level is now uncapped (default 128; higher = more regions).

nodejs/index.d.ts

@@ -30,7 +30,7 @@ export interface Options {
   adaptiveWindow?: number;
   /** Adaptive sensitivity: percent below the local mean (default 15). */
   adaptiveT?: number;
-  /** Watershed clustering: hierarchy cut level 0..=255 (higher = more regions, default 128). */
+  /** Watershed clustering: hierarchy cut level (default 128; higher = more regions, uncapped). */
   watershedDetail?: number;
 }