fix(career): gen check after error-branch json + closeBook invalidates in-flight (Creed F1b/F2b)

F1b (MEDIUM): the error path (non-ok response) lacked a gen check after
res.json() completed. A stale 404's json() could finish after a newer booking
had incremented _ppBookGen, and the error handler would still revert the newer
pref to 'any'. Fix: `if (gen !== _ppBookGen) return;` immediately after the
error-branch `await res.json().catch(...)`. Test: json() side-effect bumps
_ppBookGen (simulating a new booking racing in), verifies pref stays 'standard'.

F2b (LOW): closeBook() dismissed the poster but left _ppBookGen unchanged,
so a still-pending successful bookGig response could land after dismissal and
reopen the overlay / repopulate _ppGigProposal. Fix: `++_ppBookGen` in
closeBook(). Test: pending request fires, gen bumped (simulating closeBook),
response resolves, asserts _ppGigProposal stays null.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H2bM5jSbMskpdxm2CmuQVj

plugins/career/screen.js

@@ -780,6 +780,7 @@
     function closeBook() {
         _ppBook = null;
         _ppGigProposal = null;   // a dismissed poster is a dismissed booking
+        ++_ppBookGen;             // invalidate any in-flight bookGig request
         const overlay = $('pp-overlay');
         if (overlay) { overlay.classList.add('hidden'); overlay.innerHTML = ''; }
         if (_ppReturnFocus && typeof _ppReturnFocus.focus === 'function' &&
@@ -1138,6 +1139,7 @@
             if (gen !== _ppBookGen) return; // stale response — a newer request supersedes this one
             if (!res.ok) {
                 const err = await res.json().catch(() => ({}));
+                if (gen !== _ppBookGen) return; // stale — superseded while awaiting error json()
                 if (res.status === 404) {
                     // No-match 404: revert tuning pref to 'any', re-render poster to match
                     _ppGigTuningPref = 'any';