fix(notify): name the binding window and weekly headroom

[lroolle]

What & why

A spent 5h session window is not an exhausted week. Current Claude Code may offer /low-priority at that wall, but the gated offer, active state, and separate allowance are not present in /api/oauth/usage. ccpace should therefore state the relationship it can prove without impersonating session state.

This PR changes the block to say 5h capped · 47% of 7d left · back @Wed 2 04:00, renders endpoint values at or above 100 as cap, and suppresses 100-to-101 delta noise.

It also fixes a concrete notification contract bug: producers emitted five_util, five_delta, and reset_time, while the formatter read utilization, delta, and reset_short, producing messages such as 0% (+0%) reset. Notifications now use canonical window, utilization, reset_at, and reset_time fields, retain the old aliases for existing custom hooks, and carry a stable custom-notifier event ID such as full:work:5h:<reset>. The watch frame renders through the same formatter, so it cannot drift separately again.

Sibling implementation: thevibeworks/claude-code-statusline#38 can prove /low-priority offer/active state from the current session transcript; ccpace deliberately cannot and does not claim it.

Verification

• make check: 85 passed
• uv build: wheel and sdist built
• real cached 101% / 53% / scoped-100% payload replayed through the block
• git diff --check passes
• staged privacy scan found no credentials, session IDs, emails, account names, or local paths

Cache follow-up: 5h and scoped caps no longer freeze the account. Only aggregate 7d exhaustion without a paid path is terminal; manual refresh and a newer shared statusline cache evict that snapshot. Five polling regression tests cover these boundaries.