feat: step buddy per refresh, with configurable step rate

[jpboliv]

Problem

Rocky looked frozen. Animation poses were keyed to wall-clock ticks (0.5–2s), but Claude Code only re-runs the statusline every ~8–11s during activity (measured by instrumenting the wrapper). Sub-2s ticks sampled every ~10s = coin-flip pose changes at best, fully frozen when idle. The fast moods (reacting 600ms, celebrating 500ms) played entire cycles between refreshes — invisible.

Fix

• buddy.frame counter in state; statusline.js bumps it once per invocation (skipped when mode is off), merged into the same update() as the milestone stamp.
• renderBuddy keys arm poses, gait, and dance beats off the frame counter — every host refresh now visibly changes the pose. Mood windows and quip rotation stay wall-clock.
• armsTick/fastGait/tick config removed — per-mood speed differences were meaningless at ~10s sampling.
• readState() prunes the retired buddyStyle key (left behind by a97d039); next write self-cleans old state files.
• README cadence note updated.

Step rate setting (new)

Per-refresh stepping can look frantic during fast refresh bursts, so "how often Rocky steps" is now configurable:

• buddy.stepSeconds in state throttles the frame bump: advance at most once per that many seconds, stamped in buddy.lastStepAt. 0/absent/invalid = every refresh (default, unchanged behavior).
• New /eridian:buddy <seconds> command (scripts/buddy-speed.js + commands/buddy.md, mirrors mode.js): set, 0 to reset, no arg prints current, rejects garbage/negatives.
• Rocky can only slow relative to host cadence, never speed up — the statusline can't run itself.

Verification

• TDD: throttle + command tests watched failing first, then green — 126/126 pass, lint + prettier clean.
• End-to-end: real statusline wrapper run 3× back-to-back — pose flips on every consecutive invocation; with /eridian:buddy 2, three rapid refreshes hold the frame and a refresh after 2.1s advances it; reset restores per-refresh stepping.

🤖 Generated with Claude Code