docs: feature lists describe the catalogue that actually ships

[argszero]

Summary

Four carriers still describe this project as shipping DeepSeek pricing only, with every other vendor left for the reader to configure:

Carrier	Was	Problem
README.md (feature list, "透明计费")	"内置 DeepSeek 官方 CNY 定价，支持高峰时段计价"	The front page names one vendor
README.en.md (Features, "Transparent billing")	"built-in DeepSeek official CNY pricing with peak-hour pricing support"	same, English side
docs/user-stories.md (§3 capability list)	"DeepSeek 官方 CNY 价；高峰时段计价"	mirrors the same line
docs/plan-api-matrix.md (§3)	"内置 DeepSeek 官方 CNY 定价…；其余厂商可按同格式配置"	reads as: the other vendors are not configured

docs/plan-api-matrix.md §3 also listed the provider roster as deepseek、zhipu(glm)、openai、anthropic、google、bytedance、minimax、aliyun 等 — eight names, two of which (bytedance, aliyun) are not the ids the config uses (bytedance-ark, aliyun-bailian), and two real ones (moonshot, xai) missing. §4's model-family roster was missing Kimi and grok.

The example config ships 10 providers / 16 plans / 24 models, with 13 rows priced in CNY and 11 in USD; the four international vendors became selectable in #414 and the new-generation rows landed in #415. The old wording was accurate when written — it is incomplete now, and incomplete in the direction that undersells the feature list.

Changes

Docs only — 4 files, +6 / −6, no behaviour change:

• The three billing lines now say the vendor price lists ship with the release and each is recorded in its own currency (CNY / USD), instead of naming DeepSeek alone.
• plan-api-matrix.md §3: "各厂商价目已随 config/config.example.toml 预置…新增厂商只需按同格式补 [[models]]", and the provider roster is spelled with the real ids, complete and exact.
• plan-api-matrix.md §4: adds Kimi and grok to the family roster.

No counts are restated in prose. The counts are owned by the config and by catalog_gate's MODEL_COUNT / PLAN_COUNT; putting numbers on the front page is the stale-copy family this repo has cleaned up before, so the prose points at the source of truth instead.

Tests

• cargo test — 579 passed / 0 failed (same count as main: docs-only)
• cargo fmt --check — clean
• No new tests: this is prose. The claims were verified mechanically instead, and both directions were checked so the roster cannot be merely "not wrong":
  • every provider id named in plan-api-matrix.md exists in config/config.example.toml — 10 named, 10 present;
  • every provider in the config is named — nothing left out (the "等" is no longer load-bearing);
  • each of the 10 providers has at least one [[models]] row, so none of them is a name with no catalogue entry behind it.

Checklist

• Branch name follows the convention (docs/)
• Commit message follows Conventional Commits
• Single responsibility (one axis: the feature lists describe one vendor instead of the shipped catalogue)