* fix: skip fixed footer height in auto-content-height calculation
When the Page component's footer has position: fixed, it is removed
from the normal document flow and should not be subtracted from the
available content height. Previously, the footer's offsetHeight was
always subtracted, causing incorrect height calculation for fixed
footers.
Also reset shouldAutoHeight before recalculating to prevent stale
state on hot reload.
Fixes#4576
* fix: replace getComputedStyle footer height check with footerFixed prop
Use an explicit `footerFixed` boolean prop instead of runtime
getComputedStyle detection to determine whether the footer height
should be excluded from content height calculation. This avoids
unreliable style queries and makes the behavior deterministic.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
leo