Full-height dashboard columns so drops land in short columns (v1.3.4)

[Krippler]

Bug

In a 3-column-capable window with a 2-column layout, you couldn't move a card out of the tall column into the short one (or reliably into a new column). Columns were only as tall as their content (align-items: flex-start), so the empty space beneath a short column wasn't part of any column and rejected drops.

Root cause (reproduced)

A drop-target probe at 1940px with one card in column 1 and six in column 2:

col heights: [237, 566, 0]
probe (x,y → column):
  (158, 426) → 0     (158, 676) → -1   ← dead zone below the short column
  (158, 842) → -1    ← dead zone

Points below column 1's content hit -1 (no column). Card can't be dropped there.

Fix

• .dashboard { align-items: stretch } — every column now spans the full dashboard height, so its entire width is a valid drop target. After the fix the same probe returns col 0 at every Y (no dead zones); heights [566,566,566].
• Widened the while-dragging ＋ new-column rail 48→60px for easier targeting.

At rest there's no visual change (stretched columns are invisible — no background/border; cards still stack at the top).

Verification

Headless browser at 1940px:

• ✅ Drop-target probe: no dead zones below the short column
• ✅ Dropping a card into the short column at a low Y now works
• ✅ Dropping into the 60px full-height rail creates a 3rd column
• ✅ Rest layout visually unchanged
• ✅ 122 tests green

Ships as 1.3.4. On merge the auto-release publishes 1.3.4 / 1.3 / 1 / latest.

🤖 Generated with Claude Code

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Generated by Claude Code