fix(terminal): remove the unreachable copyTerminal(), closing out #322

The last two items of #322: copyTerminal() copied the entire buffer but
was wired to no button, shortcut or call site anywhere, and it wrote
through navigator.clipboard directly, which is undefined on the
plain-HTTP LAN install, so it would have failed there even if it were
reachable. Everything that actually copies goes through
copyTerminalSelection() and _copyText's execCommand fallback; whole-
buffer copy, should anyone want it, is a selectAll() away from that
same working path.

Closes #322

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

src/web/public/terminal-ui.js

@@ -3878,21 +3878,6 @@ Object.assign(CodemanApp.prototype, {
     return ok;
   },
 
-  async copyTerminal() {
-    try {
-      const buffer = this.terminal.buffer.active;
-      let text = '';
-      for (let i = 0; i < buffer.length; i++) {
-        const line = buffer.getLine(i);
-        if (line) text += line.translateToString(true) + '\n';
-      }
-      await navigator.clipboard.writeText(text.replace(/\n+$/, '\n'));
-      this.showToast('Copied to clipboard', 'success');
-    } catch (err) {
-      this.showToast('Failed to copy', 'error');
-    }
-  },
-
   _syncMobileHelperTextareaToCursor() {
     if (!MobileDetection.isTouchDevice() || !this.terminal?.element) return;
     try {