chore: initialize frontend repo with teaching terminology updates

Add the current frontend codebase with a baseline .gitignore and update piano-specific UI terms to teaching-oriented terms for the current product context.

Made-with: Cursor

weapp/utils/htyWeappLog.js

@@ -0,0 +1,25 @@
+const log = require('./log.js')
+
+function shortTail(s, tailLen) {
+  tailLen = tailLen || 8
+  if (!s) return ''
+  var t = String(s)
+  return t.length <= tailLen ? t : '…' + t.slice(-tailLen)
+}
+
+function logWeapp(phase, payload) {
+  try {
+    var line = typeof payload === 'string' ? payload : JSON.stringify(payload)
+    if (line.length > 1500) {
+      line = line.slice(0, 1500) + '…(truncated)'
+    }
+    log.info('[HtyWeapp]', phase, line)
+  } catch (err) {
+    log.info('[HtyWeapp]', phase, String(payload))
+  }
+}
+
+module.exports = {
+  shortTail: shortTail,
+  logWeapp: logWeapp
+}