website: Fix deep links

Fixes issue #12.

Issue: Navigating directly to an anchor link does not work on Chrome.

Diagnosis: Chrome issue that interacts with svelte-toc. https://github.com/janosh/svelte-toc/issues/57

svelte-toc (the table of contents library) scrolls the ToC as the page is scrolled. That is, if your ToC is so long as to have its own scroll bar, if you scroll way down to the last heading on the page, the ToC div will also automatically scroll to its bottom.
svelte-toc does this by listening for scrollend events and then making the ToC scroll to whatever the main page is looking at.
With Chrome + CSS property scroll-behavior: smooth, navigating directly to an anchor link fires several scrollend events upon page load. (I'm not sure why.)
Chrome can't handle simultaneous scrolls even if they're on disjoint containers, so the immediate scrollend events cause the ToC to scroll, which cancels the scroll of the main page body to the anchor.

Potential fixes (besides waiting to see if the svelte-toc maintainer figures out a way to work around this):

Delay mounting svelte-toc for a second until the initial scrollend events have presumably passed (this is what I chose in this PR)
Turn off smooth scrolling (so going to an anchor link jumps straight to it instead of scrolling there)
Turn off smooth scrolling initially, then dynamically enable it later after waiting a second.
Turn off svelte-toc's auto-scroll (via its keepActiveTocItemInView flag). This is mostly OK but would affect our sections with very long ToCs (e.g., "training sample games") and people using very short screens
This seems to only happen with Svelte and not, say, SvelteKit, so we could totally refactor our website (not worth it)

Changes

Delay mounting svelte-toc
Also, deep-links can scroll to the wrong place because the <GameList />s next to each Go board are dynamically loaded and shift the layout. To fix this, I add filler rows to the <Game List /> until the actual games are populated.

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