docs: correct rrule drift (code uses ical.js RecurExpansion) + minor fixes

Recurrence expansion uses ical.js ICAL.RecurExpansion, not the rrule
library (never installed/imported). Also fix playwright-cli path
(/usr/bin), prod-compose service count (two, post-Redis-removal), and
CI job count (six). Found via /gsd-docs-update --verify-only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.planning/config.json

@@ -7,7 +7,7 @@
   "firecrawl": false,
   "exa_search": false,
   "git": {
-    "branching_strategy": "phase",
+    "branching_strategy": "milestone",
     "create_tag": true,
     "phase_branch_template": "gsd/phase-{phase}-{slug}",
     "milestone_branch_template": "gsd/{milestone}-{slug}",