Adds credits status bar

[mcowger]

Adds a status bar item to display the user's Kilo Code credits.

• Implements a CreditsStatusBar class to manage the status bar item, including refreshing the balance and displaying it to the user.
• Fetches balance data periodically and updates the status bar with the current balance and consumption rate (if non zero over the last 5 minutes).
• Adds a command to manually refresh the balance (and can be refreshed with a click).
• Formats the balance for display in a compact notation.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0c13ac1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
kilo-code	Minor

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[mcowger]

Tagging @kevinvandijk per request.

[mcowger]

pinging @kevinvandijk for review