fix: price impact scale normalization, batch concurrency/rate-limits, and anomaly NaN threshold

[ushpraise]

What this fixes

• Bug: AMM price impact compares decimal values at different scales #1011: In AMMCalculator.computePriceImpact(), spot price and effective price strings were parsed into scaled integers using differing scales (e.g. scale 1 for integer price strings without decimal points vs scale 10^12 for fractional price strings), resulting in incorrect price impact computations (e.g. reporting 0.00% instead of 9.00% for 100 swap on a 1000/1000 pool).
• Bug: invalid invoice concurrency limits can stall batch processing #1010: InvoiceBatchProcessor accepted invalid concurrency limits (non-positive integers, fractional numbers, NaN, and ±Infinity) and launched worker loops unbounded up to maxConcurrent even when only a few invoices were queued, causing dispatch failures or stalling the event loop on huge limits.
• Bug: batch workers can dispatch before the shared 429 pause expires #1009: InvoiceBatchProcessor allowed global 429 pause windows to be shortened if subsequent requests received smaller retryAfterMs values, workers sleeping on earlier deadlines did not recheck extended deadlines upon waking, and invalid/negative/non-finite retry and pause options were accepted.
• Bug: NaN sensitivityThreshold silently disables anomaly alerts #1008: In AnomalyDetector, the sensitivityThreshold validation this.sensitivityThreshold <= 0 || this.sensitivityThreshold > 1 accepted NaN because comparison with NaN evaluates to false, which silently classified all anomaly scores as "normal".

What changed

• src/ammCalculator.ts: Normalized spotScaled and effectiveScaled to a common scale before computing the percentage price impact.
• src/invoiceBatchProcessor.ts:
  • Validated that maxConcurrent is an integer >= 1, throwing RangeError otherwise.
  • Capped the initial launch count to Math.min(maxConcurrent, invoiceIds.length).
  • Added isValidPauseMs validation and safe fallback in retryAfterMs for non-integer/negative values.
  • Validated rateLimitPauseMs as a non-negative integer.
  • Enforced monotonic rate-limit deadlines using Math.max(pausedUntil, nextPausedUntil) and implemented waitForGlobalPause() to re-check the global pause deadline after waking.
• src/anomalyDetector.ts: Added !Number.isFinite(this.sensitivityThreshold) check to reject NaN and infinite values while preserving valid thresholds in (0, 1].
• Added test suites:
  • test/ammCalculator.test.ts: Added normalization regression test for estimateSwapOutput.
  • test/invoiceBatchProcessor.concurrency.test.ts: Added tests for maxConcurrent validation and initial launch capping.
  • test/invoiceBatchProcessor.rateLimit.test.ts: Added tests for rateLimitPauseMs validation, malformed retry-after fallback, monotonic global pause enforcement, and wake-up pause re-checking.
  • test/anomalyDetector.nan.test.ts: Added tests for NaN sensitivity threshold rejection and upper boundary acceptance.

Testing

• npx vitest run test/ammCalculator.test.ts: 13/13 tests passed.
• npx vitest run test/invoiceBatchProcessor.concurrency.test.ts: 7/7 tests passed.
• npx vitest run test/invoiceBatchProcessor.rateLimit.test.ts: 12/12 tests passed.
• npx vitest run test/invoiceBatchProcessor.test.ts: 6/6 tests passed.
• npx vitest run test/anomalyDetector.test.ts: 25/25 tests passed.
• npx vitest run test/anomalyDetector.nan.test.ts: 2/2 tests passed.
• All 65 related tests passed concurrently.
• npm test: 110/110 tests passed across client, retry policy, and network environment suites.

Issues

closes #1008
closes #1009
closes #1010
closes #1011

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