design(calendar): render two-week agenda as a dense ruled list, not floating cards

[johnpc]

What

The Calendar "Two weeks" agenda rendered each dated task as a full-width floating board card (border + drop-shadow + radius, title stacked above its project chip, padding: 12px 14px, gap: 8px). In a single-column agenda that produced tall rows with the content clustered on the left and a large empty right region on desktop, and only ~3 tasks visible per screen on mobile.

Calendar was the last core task-list surface still using floating cards after My Tasks (#220) and the List view (#109) were made dense. This brings it in line, scoped to .calendar__task:

• Strip the card's border / box-shadow / border-radius / surface fill; give each row a single border-bottom hairline (--tf-border) + a --tf-surface-2 hover highlight, and zero the intra-day .calendar__list gap so the dividers butt into one continuous ruled list. (Days stay separated by the existing .calendar__days gap + day header.)
• Lay the row out horizontally — title on the left, project chip + assignee avatar aligned to the trailing edge — matching the My Tasks / Search row rhythm. The title ellipsizes so a long name never pushes the chip off-row.

Token/CSS-only; no markup, logic, or schema change. The Month grid is untouched.

Before / After

Desktop — 6 days now fit above the fold vs 3 before; no empty right region.

Before	After

Mobile

Before	After