docs(phase-15): complete phase execution — verification passed

- VERIFICATION.md: 3/3 must-haves verified, 124/124 tests green
- ROADMAP.md: Phase 15 marked complete
- STATE.md: advanced to post-phase state

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/settings.local.json

@@ -1,8 +1,12 @@
 {
   "permissions": {
     "allow": [
+      "Bash(*)",
       "WebSearch",
-      "Bash(xargs wc:*)"
+      "Bash(xargs wc:*)",
+      "Bash(claude plugin *)",
+      "Bash(where claude *)",
+      "Bash(cmd /c \"claude plugin marketplace add JuliusBrussee/caveman && claude plugin install caveman@caveman\")"
     ]
   }
 }