Standardize --json behavior

[seroperson]

Closes #1151

Summary

Three CLI surface differences collapsed into one:

1. gitt miner {post,check,score} shipped --json-output; every other command uses --json. Renamed everything to the --json.
2. The miner commands emitted {"success": false, "error": "<string>"}; issue commands emit {"success": false, "error": {"type": ..., "message": ...}}. Unified everything on the nested shape.
3. Click's own parse errors (Invalid value for '--id', No such option, Missing option) printed plain text to stderr regardless of --json. Sometimes we throw such exceptions by ourselves. Added JsonAwareAliasGroup at the root so parse errors surface as the canonical JSON envelope when --json is in argv. Without --json the default Click rendering is preserved.

Centralized the envelope helpers in a new gittensor/cli/json_output.py (emit_json, emit_error_json, wants_json_output, click_error_type). Issue commands, miner commands, and the root group now import from one source.

Before / After

Before:

$ gitt issues list --json --id abc

Error: Invalid value for '--id': 'abc' is not a valid integer.

After (standardized json error handling behavior across the whole codebase):

$ gitt issues list --json --id abc

{"success": false, "error": {"type": "bad_parameter", "message": "Invalid value for '--id': 'abc' is not a valid integer."}}

Testing

• test_click_parse_errors_stay_human_without_json_flag - asserts plain-text rendering is preserved when --json is absent
• test_click_parse_errors_emit_canonical_json - asserts that Click's own arg-parsing errors emit the canonical {success: false, error: {type, message}} envelope when --json is in argv.

Other existing tests were updated according to the new behavior.