Two gaps closed:
1. /memory (resume): json field was None, emitting prose regardless of
--output-format json. Now emits:
{kind:memory, cwd, instruction_files:N, files:[{path,lines,preview}...]}
2. /providers (resume): had a spec entry but no parse arm, producing the
circular 'Unknown slash command: /providers — Did you mean /providers'.
Added 'providers' as an alias for 'doctor' in the parse match so
/providers dispatches to the same structured diagnostic output.
3. /doctor (resume): also wired json_value() so --output-format json
returns the structured doctor report instead of None.
Continues ROADMAP #26 resumed-command JSON parity track.
159 CLI tests pass, fmt clean.
7587f2c1eb