dedupe: single canonical hyperhive.svg for favicon + og + hero

mara nit on #1: the three SVGs in static/ were identical copies
(md5 1108d7bd79ca…). Dropped favicon.svg + hex-mark.svg; kept
hyperhive.svg as the single source. Both consumers now point at
it: `<link rel="icon">` and the hero's `load_data(path="static/
hyperhive.svg", format="plain")`.

Also fixed: the original `load_data(path="hex-mark.svg")` would
have failed at build time anyway — Zola's `load_data` resolves
from project root, so files in `static/` need the full prefix
+ `format="plain"` to come back as raw markup. Build was never
validated locally (remote-builder unreachable from agent), so the
typo would have surfaced on the operator's first `nix build`.
Caught it during the dedupe pass.

If a future visual divergence is wanted (simpler favicon,
titled og:image), can split back into named copies then.

README.md

@@ -31,9 +31,8 @@ templates/
 sass/
   main.scss          # theme — Catppuccin Mocha + amber accent
 static/
-  favicon.svg        # hyperhive hex motif (copy of dashboard branding)
-  hex-mark.svg       # same SVG, used inline in the hero
-  hyperhive.svg      # og:image
+  hyperhive.svg      # single canonical hex motif — favicon + og:image
+                     # + inline hero (via Zola `load_data`)
 flake.nix            # `nix build` → site dist, `nix develop` → zola shell
 ```