feat: livelier character animations and improved timing

[Commandershadow9]

Motivation

Characters currently feel static — they sit frozen for 2–4 minutes between movements, status bubbles vanish after just 2 seconds (too fast to read), the matrix spawn effect is nearly invisible at 0.3s, and idle characters are completely still with no animation.

This makes the office feel lifeless, even when agents are actively working.

Changes

All changes are isolated to constant values and one small animation loop — no architectural changes, no new dependencies.

Timing constants (webview-ui/src/constants.ts)

Constant	Before	After	Why
TYPE_FRAME_DURATION_SEC	0.3	0.18	Faster, more energetic typing animation
SEAT_REST_MIN/MAX_SEC	120–240	30–70	Characters get up and wander more often
WANDER_PAUSE_MIN/MAX_SEC	2–20	1–6	Smoother, more natural roaming
WANDER_MOVES_BEFORE_REST_MIN/MAX	3–6	5–12	Characters explore further before sitting
INACTIVE_SEAT_TIMER_MIN_SEC	3.0	1.5	Quicker idle transition
INACTIVE_SEAT_TIMER_RANGE_SEC	2.0	1.0	Less variance in idle timing
WAITING_BUBBLE_DURATION_SEC	2.0	15.0	Users can actually read tool status text
DISMISS_BUBBLE_FAST_FADE_SEC	0.3	2.0	Smoother bubble fade-out
BUBBLE_FADE_DURATION_SEC	0.5	1.5	Gentler transition when bubbles disappear
MATRIX_EFFECT_DURATION_SEC	0.3	1.8	Sub-agent spawn effect becomes clearly visible
MATRIX_COLUMN_STAGGER_RANGE	0.3	0.4	More dramatic cascading rain effect

Idle breathing animation (webview-ui/src/office/engine/characters.ts)

• New IDLE_FRAME_DURATION_SEC = 2.5 constant
• IDLE state now cycles between walk frames 0 and 1 every 2.5s
• Characters subtly "breathe" instead of standing completely frozen
• Uses existing walk sprite frames — no new assets needed

Why this matters

The core appeal of Pixel Agents is watching characters react to your development workflow. These changes make the office feel alive even during quiet moments, and ensure that important status information (tool bubbles, spawn effects) is actually visible to the user.

Test plan

• Open Pixel Agents panel, observe characters wander more frequently (~30–70s vs ~2–4min)
• Trigger a tool execution — verify status bubble stays visible for ~15 seconds
• Spawn a sub-agent (Agent tool) — verify matrix rain effect is slower and clearly visible (~1.8s)
• Leave agent idle — verify character subtly alternates between frames (breathing) instead of freezing
• Verify typing animation looks natural at the faster speed (0.18s per frame)

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