Fix loading-screen sizing shift from the Inter font swap

font-display: swap paints with the fallback font stack first, then
swaps to Inter once the 876KB variable font finishes downloading.
.loader-wordmark was already width-fixed from an earlier centering
fix, but .loader-tagline, .loader-message, and .progress-percent had
no explicit width and (more importantly) used line-height: normal,
which is derived from each font's own metrics - Inter and the fallback
stack disagree by 3-4px per line. Those three deltas summed exactly to
the .loader column's total 10px height change, which is what visibly
shifted the whole centered loading screen once the swap happened.

Gave the width-dependent elements width: 100% (matching the wordmark)
and gave all three text elements an explicit unitless line-height
(computed from font-size, not font metrics) so their box size no
longer depends on which font is currently active.

Verified empirically: forced the fallback font stack on the live page
and diffed getBoundingClientRect() against Inter for every loader
element - all width/height deltas are 0 after the fix (previously up
to 17.5px width / 10px cascaded height).

web/medmind_shell.html

@@ -209,7 +209,9 @@
 				font-size: clamp(20px, 2.3vw, 28px);
 				font-weight: 430;
 				letter-spacing: 0;
+				line-height: 1.3;
 				margin: 17px 0 clamp(36px, 6vh, 54px);
+				width: 100%;
 			}
 
 			.progress-row {
@@ -241,6 +243,7 @@
 				font-size: 22px;
 				font-variant-numeric: tabular-nums;
 				font-weight: 650;
+				line-height: 1.3;
 				min-width: 60px;
 			}
 
@@ -248,8 +251,10 @@
 				color: var(--muted);
 				font-size: 19px;
 				letter-spacing: 0;
+				line-height: 1.3;
 				margin: 24px 0 0;
 				text-align: center;
+				width: 100%;
 			}
 
 			#status-notice {