A map's share card resolves under 150 ms and draws under 300 KB for 2,000 closed and 300 open issues #6206

Measured 2026-10-26 on the forge, which runs 0.7.260: /og/map/trevato~forge.svg took resolve;dur=1064 and sent 1.9 MB. main already draws only open issues on the card, so measure again after deploy. This issue is done when a test holds the budget either way.

Done when:

• [ ] ogCard's resolve for map (src/web/pages/og.ts → mapCardInput) names its stretches (graph, marks, layout).
• [ ] The layout reuses the map page's layout cache when the open set is the same.
• [ ] A test with 2,000 closed and 300 open issues asserts resolve under 150 ms and the SVG under 300 KB.

Files: src/web/pages/og.ts, src/web/og/map.ts, test/og*.test.ts. Risk: the card is public and cached for 300 s. Keep the etag over what is drawn.