Show connected state plainly in the model picker

[TheGreatAxios]

After a successful ChatGPT browser login the picker read as if still unconnected: the Alt+A row kept its login CTA, a legacy bare codex row duplicated the credential-backed codex/default entry, and connected rows showed a misleading unknown price.

Display-state only; no auth-flow changes.

• Alt+A selector renders connected OAuth kinds as ' · N connected' instead of the browser-login CTA; rows stay listed so a second account remains reachable.
• The live catalog merge drops a legacy bare codex/xai settings row once that family has a credential-backed profile entry; the bare row stays when nothing is connected.
• Connected codex/ and xai/ picker rows state subscription billing instead of 'Pricing unknown'.

Fixes CL-5606

[linear-code]

CL-5606

[TheGreatAxios]

Audit: NEEDS-WORK (colon-less id mis-parse)

Finding: describeModelCatalogOption (src/tui/model-catalog.ts:327) parses the provider with option.id.slice(0, option.id.indexOf(":")). For a colon-less id indexOf returns -1, so slice(0, -1) silently drops the last character and the row is priced/attributed to a truncated provider (e.g. the codex/ subscription-billing branch can miss). Fix: option.id.split(":")[0]-style exact parse, which returns the whole id when there is no colon. I will push this fix plus a colon-less regression test to this branch.

Confirmed (no change requested): the connected-state plain wording, the provider/model:model id shape for built rows, and the warning-override path all read correctly; only the provider parse needs the fix.