finish phase 4: drop @atproto/api dependency, lex-only errors, delete toLex and legacy validators

oxlint-suppressions.json gains a baseline entry for webpack.config.js: the
file was never previously staged/linted (lint script covers src+modules
only), and editing it exposed its pre-existing violations to lint-staged.
All suppressed counts are pre-existing; this change only removes a line.

src/features/inviteFriends/urls.ts

@@ -7,7 +7,7 @@
  * label simply drops the `https://` scheme for readability.
  *
  * Kept as a dependency-free leaf module (no #/lib/strings/url-helpers import)
- * so its unit tests stay fast and isolated from the heavy @atproto/api graph.
+ * so its unit tests stay fast and isolated from the heavy SDK graph.
  */
 
 function stripLeadingAt(handle: string): string {