PAP-56: register conference-room and artifacts as board routes

Both routes rendered "Company not found" because their root segments
were missing from BOARD_ROUTE_ROOTS, so applyCompanyPrefix never
prepended the company prefix. Add both roots and a regression test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ui/src/lib/company-routes.test.ts

@@ -64,4 +64,15 @@ describe("company routes", () => {
       "/teams-catalog/core-exec-team",
     );
   });
+
+  it("treats /conference-room and /artifacts as board routes that need a company prefix", () => {
+    expect(isBoardPathWithoutPrefix("/conference-room")).toBe(true);
+    expect(isBoardPathWithoutPrefix("/artifacts")).toBe(true);
+    expect(extractCompanyPrefixFromPath("/conference-room")).toBeNull();
+    expect(extractCompanyPrefixFromPath("/artifacts")).toBeNull();
+    expect(applyCompanyPrefix("/conference-room", "PAP")).toBe("/PAP/conference-room");
+    expect(applyCompanyPrefix("/artifacts", "PAP")).toBe("/PAP/artifacts");
+    expect(toCompanyRelativePath("/PAP/conference-room")).toBe("/conference-room");
+    expect(toCompanyRelativePath("/PAP/artifacts")).toBe("/artifacts");
+  });
 });

ui/src/lib/company-routes.ts

@@ -20,6 +20,8 @@ const BOARD_ROUTE_ROOTS = new Set([
   "u",
   "design-guide",
   "search",
+  "conference-room",
+  "artifacts",
 ]);
 
 const GLOBAL_ROUTE_ROOTS = new Set(["auth", "invite", "board-claim", "cli-auth", "docs", "instance"]);