As a user I want the training history to show a magenta heatmap so I can see my effort at a glance

[ChristopherRotnes]

Summary

Redesign `History.jsx` with the new magenta calendar heat tiers, a dynamic condensed hero showing total session count, horizontal pill filter chips replacing the Carbon MultiSelect, and styled session rows with left accent strips.

Part of #96. Depends on phase 1 (tokens + heat colors).

Priority

Medium

UI spec (Carbon g100)

• Hero: "{N} økter. Bra trykk." — "Bra trykk." in `var(--accent)`, Plex Cond 600 ~28px
• Calendar h0–h5 heat tiers: magenta rgba ramp (`rgba(238,44,128,.18)` → `#ee2c80`); today gets `1.5px solid #fff` outline; no-session cells use `var(--surface-card)` bg
• Calendar cells: explicit `borderRadius: 0`
• Filter chips: replace Carbon `MultiSelect` with horizontally scrollable pill row; active → `background: var(--accent)`, inactive → `var(--surface-card)` + subtle border
• Session rows: always-on `3px solid var(--border-subtle-wl)` left strip; filter-matched sessions → `var(--accent)` strip
• Session title in Plex Cond; time + exercise count meta in mono `var(--text-muted-wl)`

Acceptance criteria

• Hero shows live session count with "Bra trykk." in magenta
• Calendar cells render magenta heat (not green)
• Today's cell has white outline on top of its heat tier
• h0 (no session) cells use `var(--surface-card)` background
• Muscle filter renders as horizontal scrollable pill row
• Active filter pill is magenta; inactive is neutral
• Session rows have 3px left strip; filter-matched sessions show magenta strip
• Session title uses Plex Cond font
• All calendar cells have 0 border radius
• WCAG AA on all calendar heat tier text colors (h1 uses `#ff9bc5`, h2+ use `#fff`)

Out of scope

• Edit mode changes
• Re-analyse functionality changes

[ChristopherRotnes]

Implemented and verified in PR #112. Closed.