Consumption-share split in `codeburn models`, reworked per review:
- First-party routes only: the split applies to `dsh` (DeepSeek API) and
`zcode` (Z.ai plan) calls. The same model behind a gateway never had
the vendor discount, and reported-cost providers may already carry it;
the gate set stays disjoint from REPORTED_COST_PROVIDERS.
- The numbers agree by construction: both legs are shares of the stored
list-rate cost (peakUSD + offPeakUSD == costUSD, pinned in tests).
The 0.5x off-peak discount stays on the vendors' bills; nothing is
repriced here. peakCostMultiplier and OFF_PEAK_MULTIPLIER are gone.
- Calendars: unverified 2027 projections dropped; the Z.ai
2026-09-25..10-07 all-day off-peak promotion is honored as a temporary
range; deepSeekHolidayCoverageYears() plus a test fail when the
current year falls out of the holiday list.
- Output shape: JSON carries the five peak keys only on rows with a
split, so a report without DeepSeek/Z.ai first-party usage keeps its
exact historical shape; the Z.ai quota note is removed.
- The `codeburn peak` live-status command is left out (scheduling tool,
not usage tracking); it survives on a separate branch for its own PR.
* docs: move the README reference manual into docs/
* assets: designed README images and their sources
* README: tell the story first, keep the manual in docs
