fix(dashboard): tile strip back to CSS Grid for true symmetric width

Marc's v1.4.4 feedback: the tiles look better when they're all
exactly the same size and the strip begins and ends at the same
x-coordinate as the charts — the v1.4.4 `flex-1 basis-0` distribution
was close but not quite symmetric, and at 6 tiles the right edge
of the strip didn't line up with the charts below.

Switched to the v1.3-era pattern but with the modern `auto-fit +
minmax(9rem, 1fr)` form so it doesn't need explicit breakpoints:

  grid-template-columns: repeat(auto-fit, minmax(9rem, 1fr));
  gap: 0.75rem;

CSS Grid puts every tile in an identical 1fr track. Width is
literally identical, gaps are symmetric, and the strip is bounded
by the same parent box as the charts so left/right edges align by
construction. When the row no longer fits a 9 rem floor the grid
wraps to a new row — Marc explicitly tested both and prefers the
wrap over the v1.4.x horizontal-scroll for the symmetry it
preserves.

Tests + typecheck green (671/671).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "healthlog",
-  "version": "1.4.4",
+  "version": "1.4.5",
   "private": true,
   "packageManager": "pnpm@10.31.0",
   "scripts": {