feat(notice): a session wall is not a weekly wall

[lroolle]

What & why:

Claude Code 2.1.258 can offer /low-priority when the shorter 5h session window binds. The current line renders that state as 5h[101%] while a higher-ranked weekly-surplus notice can say + 47% unused, so an interrupted session reads like an invitation to spend.

This PR makes the state explicit and provenance-gated:

• render any 5h value at or above 100 as 5h[cap@04:00] and suppress the meaningless +N bump at the wall
• pin the capped 5h wall above weekly opportunity
• name /low-priority only when this session transcript carries a matching quotaLimits.lowPriorityOffer for the current reset
• distinguish offered from active through the transcript local-command result
• never guess the separate lower-priority allowance, which is absent from statusline stdin and /api/oauth/usage
• keep a fresh sibling-account escape above the lower-priority path

Real 2.1.258 offer and active transcripts were replayed against the renderer. The active frame reads + lower priority · 47% of 7d left; the offer frame reads ! 5h capped · /low-priority uses 7d. No raw transcript data enters fixtures or docs.

Checklist:

• make check passes: 491 tests
• New function added to the awk whitelist in t/helpers.bash
• No real tokens, session IDs, emails, account names, or home paths in fixtures/docs
• bash -n statusline.sh install.sh and git diff --check pass

Sibling implementation: thevibeworks/ccpace#2 states the 5h wall and weekly headroom from the account-level API, without claiming session-only eligibility.

Cache follow-up: the capped path now has one tested TTL rule in both fetch gates. stdin keeps 5h/7d live; scoped and extra-usage fields remain on a finite 120 s API cadence instead of freezing to reset.