TTY-aware output under the git porcelain rule #33

Design decision 5: pretty for humans when interactive, frozen plain contract when piped. Machine shapes are additive-only contracts; human text may evolve.

Acceptance criteria

• TTY: aligned table for keys, color accents (respect NO_COLOR); piped: current plain output byte-stable
• JSON pretty-prints on TTY, compact when piped (gh rule)
• Flag symmetry: --json accepted as alias for --jsonl on watch; dump --json documented as accepted no-op; keys --quiet prints key names only
• Completion scripts documented in README (bash/zsh/fish already work)
• Smoke asserts piped output stays plain; specs updated

Locked decisions (design interview round 2, 2026-07-18)

• Chrome level: minimal. Aligned tables, bold section headers, semantic color only (green success / red error), NO_COLOR respected. Rich styling (box-drawing, spinners) only if users ask after public.