Add --json flag to codegraph status for CI/scripting

[fuleinist]

Problem

The codegraph status command outputs human-readable text, making it difficult to use in CI pipelines or scripting contexts where machine-parseable output is needed.

Solution

Add a --json flag to codegraph status that outputs structured JSON with fields like:

• initialized: boolean
• indexPath: string (path to index directory)
• lastIndexed: ISO timestamp or null
• agentCount: number
• version: string

This is consistent with other tools in the agent ecosystem (e.g., ctx7 skills list --json) and enables scripting use cases.

Use case

CI scripts can parse `codegraph status --json` to check whether a project is properly initialized before running agents, or to verify index freshness.

[12122J]

I took a quick look at current main and noticed codegraph status already has -j, --json, but the JSON shape does not include all fields requested here (indexPath, lastIndexed, agentCount, version).

Happy to open a PR that extends the existing JSON output while preserving current fields.
Does that match what you had in mind?