Add account component to show active Claude Code login profile

[ThusharaSampath]

Summary

Adds a new `account` provider + component that detects which Claude Code account is currently logged in (macOS only) and renders a colored label on the status line.

Motivation

When using Claude Code with multiple accounts (e.g. personal Pro + work Team) and switching between them by swapping the OAuth token in the macOS Keychain, it's easy to lose track of which account a given session belongs to. This component makes that visible at a glance.

How it works

• Provider: shells out to `security find-generic-password` to read the live credentials slot (default: `Claude Code-credentials`) and each configured profile slot (defaults: `Claude Code-personal`, `Claude Code-work`). When the live token matches a saved profile slot, the provider returns that profile name. When it matches no slot, it returns `"unknown"`. Non-macOS platforms get an empty profile (component renders nothing).
• Component: maps the profile name to a color (defaults: `personal=cyan`, `work=magenta`) and renders via the standard template system. By default it hides itself when no profile is detected; configurable via `hide_unknown`.
• Caching: default TTL is 60s — Keychain shellouts are cheap but not free, and account switches are deliberate user actions.

Defaults

• Added to the default `active` list between `duration` and `version`. Users who don't want it can remove it from their `active` list (it's a no-op on non-macOS anyway).
• Profile-name and slot-name conventions match a companion setup tool (claude-switch) that manages the Keychain slots, but the component is independent — any setup that maintains the named Keychain slots will work.

Config example

```yaml
providers:
account:
cache:
ttl: 60s
active_slot: "Claude Code-credentials"
profiles:
personal: "Claude Code-personal"
work: "Claude Code-work"

components:
account:
template: "{{.Icon}}{{.Profile}}"
colors:
personal: cyan
work: magenta
default_color: gray
hide_unknown: true
```

Test plan

• `go test ./...` passes (new component has unit tests covering: hidden states, per-profile coloring, default-color fallback, custom templates/icons, empty template)
• `make lint` passes with 0 issues
• Manual smoke test with both `personal` (Pro) and `work` (Team) tokens in Keychain — component correctly renders cyan `personal` / magenta `work` based on which token is in the active slot
• Manual smoke test with no matching profile — component hides itself by default

Notes

• The provider isn't unit-tested directly because it shells out to `security`. If you'd prefer it be testable, I can refactor to inject a `keychainReader` interface — happy to do so in a follow-up.
• The component is macOS-only by design (Keychain). On Linux/Windows the provider returns an empty profile and the component renders nothing.

[Mirage20]

Shall we keep this disabled by default, as this is not a common use case?

[ThusharaSampath]

Good call — agreed. Pushed in a086efb: dropped account from the default active list (both in config.yaml and the hardcoded fallback in main.go), kept the component and provider registered, and added a commented example near the bottom of config.yaml showing how to enable it.