test: Storage + Arcade e2e load test suite

[sambabbage]

Summary

This PR now provides a production-safe, evidence-producing E2E test for the actual Storage → Arcade → Monitor → Storage lifecycle.

• Authenticated reads and writes use only STORAGE_E2E_TARGET_URL; there is no hidden second Storage backend.
• Mainnet spending requires the explicit STORAGE_E2E_ALLOW_MAINNET=true gate.
• Multi-user writes use independent deterministic identities funded with real BRC-29 wallet payments.
• Concurrent no-send transactions are broadcast through Arcade and then reconciled through Storage with sendWith.
• The final gate requires every txid to have an Arcade merkle path and the originating wallet's production listActions status to be completed.
• A mode-0600 JSON evidence artifact records sizing, timings, txids, block heights, and proof observations.
• TaskArcadeSSE now persists ProvenTxReq.notified=true after successful SSE proof ingestion and recognizes SEEN_MULTIPLE_NODES as a normal accepted state.

Production validation

Run 20260712032443 against https://storage.babbage.systems on 2026-07-12, using the upgraded production Storage and Monitor:

• 12/12 production E2E cases passed.
• 29/29 transactions were accepted, mined in block 957487, received Arcade merkle paths, and reached completed in Storage.
• Production DB correlation found 29 completed proven_tx_reqs, 29 proven_txs at height 957487, and 29 completed transaction rows.
• The block interval was unusually long: about 35 minutes. Once the block arrived, Monitor created the 29 proof rows over about 18.4 seconds.
• The live run exposed the missing persisted notified flag; that regression is fixed in this PR and covered by a focused assertion.

Metric	Result
Raw HTTPS p95, sequential / 30 concurrent	9 ms / 40 ms
Authenticated listOutputs p95, one identity / three identities	256 ms / 143 ms
Sequential writes	1.8 tx/s
Three-wide concurrent writes	9.1 tx/s
Three-identity concurrent writes	6.2 tx/s
Arcade-token concurrent ingestion	21.3 tx/s
Bounded ceiling batches	2: 14.6 tx/s; 4: 12.2 tx/s; 8: 27.5 tx/s
Proof convergence	29/29 Arcade, 29/29 Storage, 0 failures

Verification

• ts-standard on the changed TypeScript files
• wallet-toolbox build and type-check
• focused TaskArcadeSSE tests: 24/24
• wallet-toolbox non-manual suite: 124 suites, 1,127 tests passed
• production E2E suite: 12/12 passed
• branch is rebased on current main (29d614b7844a9ed113edc47462f7ed56ef03c534)

See e2e/storage/README.md for the bounded run command and environment variables.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud