visuals: print styles for the wall and the diagrams, and Phase 7 notes

- Diagrams carry a print style block, so they print as ink on white rather than
  as dark panels; the client wall and the chips go white with a hairline.
- docs/phase-7-notes.md records what batch 1 shipped, how to add a mark or an
  image, and the Lighthouse measurements taken after the batch (100/100/100/100,
  CLS 0, mobile and desktop).

(cherry picked from commit ae9282e5f62b8c7ee149ebf96f8d3f00067a49e2)

internal/web/static/site.css

@@ -1397,6 +1397,29 @@ figure.media figcaption {
 		color: #222;
 	}
 
+	/* The wall and the chips are surfaces, not decoration: on paper they go
+	   white with a hairline, and the marks keep their shape in one ink. */
+	.client-wall {
+		background: #bbb;
+		border-color: #bbb;
+	}
+
+	.client-tile,
+	.tech-chip {
+		background: #fff;
+		border-color: #bbb;
+	}
+
+	.client-name,
+	.tech-chip {
+		color: #111;
+	}
+
+	.nav-mark,
+	.pillar-mark {
+		color: #000;
+	}
+
 	a {
 		color: #000;
 		border-bottom: 0;