chore(dream-cli): cmd_list --json should emit via jq like cmd_status_json (stacked on PR-9)

[yasinBursali]

Context

Issue #398 (upstream: Light-Heart-Labs/DreamServer) was dropped from PR-1F (batch A)
because the target code does not exist on upstream/main @ d5154c3.

The `--json` branch in `cmd_list` is introduced by upstream PR Light-Heart-Labs#1000
(`feat/dream-cli-json-flag`, branch `feat/dream-cli-json-flag`). Until that PR
merges upstream, there is nothing to refactor on main.

What this follow-up tracks

Once upstream PR Light-Heart-Labs#1000 is merged:

• Refactor `cmd_list`'s `--json` emission from `printf '{"id":"%s",...}'` to the
  same `jq -n --arg ... | jq -s .` pattern used by `cmd_status_json`.
• This closes the user-installed-extension special-char escaping risk raised in
  the original issue body.

Scope

Mechanical: read manifest fields into `--arg` pairs, collect per-service jq objects,
`jq -s .` at end. No behavior change for built-in extensions.

Dependencies

• Blocked by: upstream PR feat(dream-cli): --json flag on list/status and document doctor --json Light-Heart-Labs/DreamServer#1000 merging.
• Mergeable as: a stacked PR on top of the feat(dream-cli): --json flag on list/status and document doctor --json Light-Heart-Labs/DreamServer#1000 branch, or a follow-up on main
  after feat(dream-cli): --json flag on list/status and document doctor --json Light-Heart-Labs/DreamServer#1000 merges.

Origin

Deferred from batch A PR-1F by verify-1f (dreamserver-verifier).
Original upstream issue: Light-Heart-Labs#398.

[yasinBursali]

Progress update — still blocked.

Stated dependency (upstream PR Light-Heart-Labs#1000) is currently OPEN. Even after Light-Heart-Labs#1000 merges, the jq-refactor described in this issue is separate work — Light-Heart-Labs#1000 only adds the --json flag argument-forwarding; the emission still uses printf-based JSON.

Keeping this open until Light-Heart-Labs#1000 merges, after which a follow-up PR can do the jq emission swap.