test+docs: live mainnet burn e2e verified; treasury rent-exempt requirement

End-to-end burn proven on mainnet (test wallet): build → sign → broadcast →
confirm → receipt → Essence. tx 5ddbmLRz… burned a dust token, closed the
account, returned 0.00197 SOL to the user, sent the 5% (103704 lamports) to the
treasury, recorded as Essence (Round #1 = 103704). Re-scan confirms the account
is gone; treasury credited; DB row written.

Discovered + documented: the treasury must be funded to rent-exemption before
collecting fees (a fee transfer into a 0-balance account fails "insufficient
funds for rent"). Noted in .env.example + design §3.1. Tracker: Phase 3 done.

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

infra/status/status.json

@@ -51,14 +51,14 @@
     {
       "id": 3,
       "name": "Burn Junk",
-      "state": "in_progress",
+      "state": "done",
       "items": [
         { "label": "Incinerate-only classification", "done": true },
         { "label": "Burn transaction builder (server re-validated, value-gated)", "done": true },
         { "label": "Burn-then-close flow (+ transparent 5% fee)", "done": true },
         { "label": "Stronger confirmations (destructive confirm + decode-match)", "done": true },
         { "label": "Receipt update (on-chain verified)", "done": true },
-        { "label": "Live signed burn verified e2e", "done": false }
+        { "label": "Live signed burn verified e2e (mainnet)", "done": true }
       ]
     },
     {