Docs and comments only, no behavior change:
- src/pricing.ts: fix two comments that said +20% / AWS x1.20 (the code is 2500 bps = x1.25)
- tests/peergos-billing.test.ts: fix test title and arithmetic comment (2875 millicents -> 29c, which the test already asserts)
- docs/PEERGOS-BILLING.md: hosted overage AWS x1.25; clarify that the 1.5/0.75 multipliers are timestamp-only; flag the cust-platform default as contradicting D3; add a decisions D1-D6 section
- docs/ACCOUNTING.md, docs/CUSTOMER-PORTAL.md: mark prepaid drawdown as current behavior and note the planned Stripe subscription collection (D1)