preview: serve fit_1280 + tighten timeline grid padding

InlinePreview was requesting fit_1920 for both the still image and
the video poster — roughly 3× the pixel count of what the pane
actually needs. Drop to fit_1280: still sharp inside the inline
pane (which the user resizes around 300–500px tall in practice)
while cutting payload by ~⅔.

Timeline: pull the grid wrapper padding in from `p-6 pb-24` to
`pr-2 pl-2 pb-2 overflow-x-hidden` now that the SplitGrid preview
pane sits above the grid — the old generous padding existed to
breathe under a full-screen modal that no longer renders inline.

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

web/src/lib/components/preview/InlinePreview.svelte

@@ -85,13 +85,13 @@
 			{#key vf.Hash}
 				<VideoPlayer
 					src={videoUrl(vf.Hash)}
-					poster={thumbUrl(pf.Hash, 'fit_1920')}
+					poster={thumbUrl(pf.Hash, 'fit_1280')}
 					title={photoQuery.data.OriginalName ?? pf.Name ?? ''}
 				/>
 			{/key}
 		{:else}
 			<img
-				src={thumbUrl(pf.Hash, 'fit_1920')}
+				src={thumbUrl(pf.Hash, 'fit_1280')}
 				alt={photoQuery.data.OriginalName ?? pf.Name ?? 'Photo'}
 				class="max-h-full max-w-full rounded-md object-contain shadow-2xl"
 			/>