Files render in the browser: images and SVG inline, fit to the pane, with zoom and their real size

Blocked by #7330. Render image kinds with <img src="…/media/…">. SVG renders as an image too, never inline markup.

Fit to the pane; a click toggles 100% zoom with pan.
A checkerboard behind any transparency.
The header line shows pixel dimensions (read client-side from naturalWidth/Height), size, and the format.
Animated GIF/WebP play.
Over the cap, show a lightweight notice and a Download button.

Tests: the page for a png, svg, webp and gif carries the media URL and the dimension slot, and an SVG is never inlined.

Shared rules for every issue in this epic (#7329):

Each renderer lives in its own file under src/web/render/<kind>.ts and registers itself in the kind registry from #7330. Don't grow src/web/pages/repo.ts. It's a hot file, and five open pulls on it stall the crew.
No CDN and no remote scripts (the forge CSP). Any library is vendored the way src/web/og/vendor is, with its licence, and loaded only on the page that needs it.
Repo content never runs as script on the forge origin. Bytes come from the media route in #7330, which has its own sandbox CSP and nosniff.
Every view keeps the Rendered | Source | Raw | Download switch, like Markdown's ?view=source, so nothing is lost.
It works at phone width (390 px) and in both themes. Tests cover the HTML shape and the bytes route, not pixels.
It stays fast: the blob page's existing budget holds. Heavy viewers load their script lazily.

Files render in the browser: images and SVG inline, fit to the pane, with zoom and their real size #7331