Reorganize admin nav by feature and soften light mode.

Sidebar lists one entry per feature; keep hub tabs only for sibling views (events, tickets, ranks/permissions, moderation, radio, analytics, devops). Soft cool-gray light canvas/surface replaces harsh white.

Co-authored-by: Cursor <[email protected]>

src/lib/theme-contrast.test.ts

@@ -131,7 +131,7 @@ describe("deriveAdminPalette", () => {
 		expect(admin.surface).not.toBe("#00ff00");
 	});
 
-	it("in light mode mirrors readable public surfaces", () => {
+	it("in light mode softens harsh white public surfaces", () => {
 		const admin = deriveAdminPalette(
 			{
 				color_background: "#f8fafc",
@@ -150,8 +150,8 @@ describe("deriveAdminPalette", () => {
 			},
 			"light",
 		);
-		expect(admin.canvas).toBe("#f8fafc");
-		expect(admin.surface).toBe("#ffffff");
+		expect(admin.canvas).toBe("#eef1f4");
+		expect(admin.surface).toBe("#f5f7fa");
 		expect(contrastRatio(admin.text, admin.canvas)).toBeGreaterThanOrEqual(4.5);
 		expect(contrastRatio(admin.sidebarText, admin.sidebar)).toBeGreaterThanOrEqual(
 			4.5,
@@ -169,7 +169,7 @@ describe("deriveAdminPalette", () => {
 			{ canvas: "#0b0f19", text: "#f8fafc" },
 			"light",
 		);
-		expect(admin.canvas).toBe("#ffffff");
+		expect(admin.canvas).toBe("#eef1f4");
 		expect(admin.text.toLowerCase()).not.toBe("#f8fafc");
 	});