Write one bar.perk.available point per Reset Credit #23

What to build

CodexBar writes bar.perk.available for Reset Credits as a single point: the total count, with one perk.expires_at, the earliest. Each credit has its own expiry, though. Today's telemetry has three credits, expiring 23 Oct, 30 Oct and 7 Nov 2026, but only the 23 Oct date reaches Bar UI. The other expiries only exist in CodexBar's own codex.reset_credit.expires_at series, which Bar UI doesn't read.

Telemetry Spec v1 now asks for one point per Perk when the tool identifies each one (GordonBeeming/bar-ui#19, §4 Perks). CodexBar should write one bar.perk.available point per Reset Credit, each with:

• perk.kind = reset_credit and value 1
• perk.id = the credit's ID (the value CodexBar already puts in codex.reset_credit.id)
• perk.expires_at = that credit's expiry

Bar UI adds the points up for the total and lists each credit on its own line with its expiry.

Acceptance criteria

• Each sample writes one bar.perk.available point per Reset Credit, carrying its perk.id and perk.expires_at
• With no credits, the sample still says 0 the way it does now, so Bar UI sees them run out
• Bar UI's Perks section lists each credit with its own expiry