…igger satellites

Kiln audit fixes:

Nav sidebar: replace side-stripe accent (anti-pattern) with background
tint using --event-subagent token. Smaller font, tabular-nums count.

Sidechain group: replace hardcoded #86c + side-stripe with semantic
color-mix tints from --event-subagent. Flex header with auto-margin
meta. Remove border-left accent.

Timeline rail: spine gets data-tick-count + --tick-count CSS var for
height-adaptive clamping (short sessions compact, long sessions fill
viewport). Satellite markers 3px -> 5px so color hue is perceptible
per Weber's law.

All hardcoded #86c replaced with var(--event-subagent) — one place
to change agent accent across nav, rail, turns, and sidechain groups.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

… vertically centered

Nav sidebar: agent entries now render inside the exchange group that
dispatched them (after the Agent tool_use child), not appended at the
bottom. Uses renderNavSidechainEntries to check each nav child for
matching sidechain groups via the same scMap positional lookup.

Timeline rail: flexbox vertical centering (display:flex + align-items:
center on the rail, computed height on spine via --tick-count * 12px).
Short sessions sit centered in the viewport instead of stretching
sparse ticks across the full height. Long sessions fill naturally and
cap at the available space.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>