Implement --json flag (documented but not implemented)

[TheTrustedAdvisor]

Problem

The SKILL.md and references/commands.md prominently document a --json flag:

• commands.md line 3: "All commands support --json for machine-readable output"
• SKILL.md line 20: "Use --json when parsing output programmatically"
• Every command example in SKILL.md uses --json

However, the --json flag is never defined in build_parser() and does not exist in the CLI. Running any command with --json produces an argparse error.

This is a broken API contract that affects all programmatic consumers, especially AI agents (Claude, Codex, OpenClaw) that rely on SKILL.md for tool usage.

Proposed Solution

Add a global --json flag to the top-level parser in build_parser():

parser.add_argument("--json", action="store_true", help="Output as JSON")

Then modify each cmd_* function to check args.json and output structured JSON instead of formatted text. The JSON output should include all data that the human-readable output shows.

Affected commands

• plan show → JSON weekplan with days/recipes
• search → JSON array of results with id, title, time, rating, url
• recipe show → JSON recipe object
• today → JSON array of today's recipes
• shopping show → JSON shopping list
• favorites show → JSON array of favorites
• status → JSON status object
• categories show → JSON categories map

Impact

• Severity: CRITICAL for AI agent integration
• Effort: Medium (each command needs a JSON code path)

Workaround

Currently none — programmatic consumers must parse the human-readable CLI output.