fix(compiler): never emit an empty pattern attribute

An empty pattern compiles to a regex matching only the empty string, so
every typed value becomes invalid and the form silently refuses to submit
-- no error, no request. @wrnexus/ui's input declares pattern: string = ""
and renders pattern="{pattern}", so every input that did not opt into a
pattern shipped one that could never match. This broke sign-up in a real
app, and only became visible once the dev-server client-module fix let
form enhancements mount at all.

Attributes reach the output through two emitters and both needed it: a
component's interpolated value is baked at render time, so the whole
attribute is now emitted by __wrnOptionalAttr, while a page's static
element is dropped at compile time. Component mounts are excluded, where
the value is a prop being passed down rather than an attribute.

minlength/maxlength/min/max/step/inputmode/accept get the same treatment --
inert when empty, but meaningless too.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

editors/vscode/src/extension.bundle.cjs

@@ -1,4 +1,4 @@
-// WRN editor extension source hash: 6c652a0d490112180d2167de7a6bbc8ba179343ee313c4b51812958bcd941b83
+// WRN editor extension source hash: 59ff54353ed4f50aa53f3731e232726d55549936b2edf8958beb407cc4fdf9d2
 // WRN editor extension generator hash: 456d1d614e44e5fb1f19b784176c09cf2ade9b64ef73a17934c2698150b62728
 "use strict";
 var __commonJS = (cb, mod) => () => (mod || cb((mod = { exports: {} }).exports, mod), mod.exports);