Add pretty JSON output flag

[MyTH-zyxeon]

Summary

• adds a JsonPretty output mode using serde_json pretty serialization
• adds a global --pretty flag that conflicts with --human
• documents compact JSON, pretty JSON, and human output examples

Validation

• cargo fmt -- --check
• cargo test: 11 passed
• cargo run --quiet -- info --pretty: produced indented JSON
• cargo run --quiet -- info --human --pretty: exits with clap conflict status 2

Closes #3

[abhicris]

Welcome to kcolbchain, @MyTH-zyxeon — glad you're here. 🌱

Here's what happens from this PR:

1. Our automated review looks for obvious issues (tests, secrets, size) within a couple of hours.
2. If it's clean and CI passes, we merge without back-and-forth.
3. If we need changes, we'll leave a specific comment — not a generic nit. Push another commit and we re-review.

While you wait:

• Run the repo's tests locally (see the repo README.md).
• Keep the PR scoped to one concern — bigger PRs land slower.
• Don't commit tokens or .env contents.

What happens after your first merge

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• At 2+ merged PRs you're a Regular; at 5+ you're a Fellow — Fellows are the pool we invite first for paid research, partner-org gigs, and grant-funded work. Details: https://kcolbchain.com/docs/org-contribution-policy.html
• Looking for what to pick up next? https://kcolbchain.com/invitations/ lists open help-wanted / good-first-issue across every kcolbchain repo.

Thanks for writing the code. We're building this to last.

[abhicris]

🤖 Audit verdict: safe

Straightforward feature addition using standard library functions with no malicious code, credential leakage, or supply-chain risk.

Audited by the kcolbchain PR pipeline. See pipeline docs.