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>

.env.example

@@ -45,6 +45,9 @@ QUOTE_MAX_AGE_MS=15000                 # skip stale quotes older than this
 # ---- Protocol fee (§3.1) — transparent, in-tx, non-custodial ---------------
 # The treasury receives ONLY the fee SOL (never user funds). Swap it for a
 # multisig before real volume. The fee is shown in the preview before signing.
+# IMPORTANT: fund the treasury once to rent-exemption (>= ~0.0009 SOL) BEFORE it
+# collects fees — a fee transfer that would leave a 0-balance account below the
+# rent-exempt minimum fails the whole tx ("insufficient funds for rent").
 PYRE_TREASURY_WALLET=122CNV5ZLu6fqZFpEMUdUSQwDv2zs23pkYQhkNtSQk5k
 PYRE_FEE_BPS=500                       # 5% of reclaimed rent
 PYRE_SWAP_FEE_BPS=100                  # 1% on swaps (proceeds still go to user)