feat(web): polish the WASM site - UX, help, parsing, assets

- About panel (collapsible, closed by default with a pulsing "Help" badge)
  explaining the tool; the `help` command now prints a full command reference
  instead of "HELP" (benefits the CLI too).
- Live generation as you type; Store button; masked output that stays mono-width
  (gen masks only the password column, never the header); command history with
  Up/Down (persisted); console auto-scroll; Export fixed (uses `dump`); Import.
- Name field normalizes to its canonical parsed form on blur; quick-gen and Store
  resolve the real entry name, so a leading prefix like `*P0 test1` is handled
  correctly (new hel_parse / hel_parse_name wasm helpers).
- Parser: prefix-only forms now parse with defaults - `*P0 test1` ->
  `*P0 test1 R 99 <today>`, `*P0 test1 R`, `*P0 test1 20R` - via new qpname/npname
  rules mirroring qname/nname; the fully-qualified form is unchanged.
- Favicons + web app manifest + enso asset; pkg rebuilt.

helwasm/assets/site.webmanifest

@@ -0,0 +1,11 @@
+{
+  "name": "LesS/KEY — password generator",
+  "short_name": "LesS/KEY",
+  "icons": [
+    { "src": "./icon-192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "./icon-512.png", "sizes": "512x512", "type": "image/png" }
+  ],
+  "theme_color": "#0a2540",
+  "background_color": "#f4f0e8",
+  "display": "standalone"
+}