feat: configurable footer line 2 & expose plan quotas (weekly/5h) to status_line.command

[YueDeity]

Summary

Follow-up to #2255 (shipped in 0.30.0, thanks @he-yufeng!). While building a custom
footer with [status_line] I ran into three gaps. All are about making the footer
fully customizable for status_line.command users.

1. Footer line 2 is hardcoded and cannot be hidden

status_line.items / status_line.command only control line 1. Line 2's
right side is always formatContextStatus(state.contextUsage, state.contextTokens, state.maxContextTokens) (see FooterComponent.render), with no way to hide or
customize it.

Once a user renders their own context bar via status_line.command, the built-in
context: 45% (114k/256k) on line 2 shows the same data twice.

Ask: a way to hide or reconfigure line 2, e.g.

[status_line]
line2 = false            # hide the second footer line entirely
# or make context a slot: items = [...], line2_items = ["context"]

2. statusLinePayload does not include plan quotas

Current payload (from statusLinePayload() in the footer component):

{ "model", "cwd", "gitBranch", "permissionMode", "planMode",
  "contextUsage", "contextTokens", "maxContextTokens", "sessionId", "version" }

The managed-plan quotas shown by /usage and on footer line 2 (e.g. 25% wk · 4% 5h)
are not exposed, so command scripts cannot render them. The data already exists
client-side via GET https://api.kimi.com/coding/v1/usages
(IOAuthService.getManagedUsage → { summary, limits[], extraUsage },
rows shaped { name, window, used, limit, resetAt }).

Ask: include a quota snapshot in the payload, e.g.

"quota": {
  "weekly": { "used": 37, "limit": 100, "resetAt": "..." },
  "limits": [ { "windowMinutes": 300, "used": 11, "limit": 100, "resetAt": "..." } ]
}

3. A refresh-interval setting for quota data

Quota values change slowly (per-minute granularity is plenty), but
status_line.command runs every second and must stay under 300ms — far too tight
for an HTTP call per run. If the engine polls quotas itself and serves a cached
snapshot to the payload, scripts stay fast and the API stays calm.

Ask: something like

[status_line]
quota_refresh_seconds = 120   # engine-side quota poll interval; 0 disables

Current workaround (fragile)

My script reads ~/.kimi-code/credentials/kimi-code.json, calls
/coding/v1/usages directly, and caches the result for 2 minutes with a
detached refresher. It works, but it re-implements auth and depends on internal
file formats — hence this request.

Environment

• kimi-code v0.31.0
• macOS (darwin arm64)