feat(desktop): stabilize connection workspace state

Absorb the local workspace drift for connection session handling, database switching, inspector readability helpers, and the bounded add-key preview flow.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/desktop/src/lib/database-switcher.test.ts

@@ -0,0 +1,74 @@
+import { describe, expect, it } from "vitest";
+import { buildDatabaseSwitcherLabels } from "./database-switcher";
+
+describe("database switcher helper", () => {
+  it("returns the default operator range from db0 through db15", () => {
+    expect(buildDatabaseSwitcherLabels(0)).toEqual([
+      "db0",
+      "db1",
+      "db2",
+      "db3",
+      "db4",
+      "db5",
+      "db6",
+      "db7",
+      "db8",
+      "db9",
+      "db10",
+      "db11",
+      "db12",
+      "db13",
+      "db14",
+      "db15",
+    ]);
+  });
+
+  it("keeps an active out-of-range database visible and numerically ordered", () => {
+    expect(buildDatabaseSwitcherLabels(23)).toEqual([
+      "db0",
+      "db1",
+      "db2",
+      "db3",
+      "db4",
+      "db5",
+      "db6",
+      "db7",
+      "db8",
+      "db9",
+      "db10",
+      "db11",
+      "db12",
+      "db13",
+      "db14",
+      "db15",
+      "db23",
+    ]);
+  });
+
+  it("normalizes negative or fractional inputs back to safe labels", () => {
+    expect(buildDatabaseSwitcherLabels(-3)).toEqual([
+      "db0",
+      "db1",
+      "db2",
+      "db3",
+      "db4",
+      "db5",
+      "db6",
+      "db7",
+      "db8",
+      "db9",
+      "db10",
+      "db11",
+      "db12",
+      "db13",
+      "db14",
+      "db15",
+    ]);
+    expect(buildDatabaseSwitcherLabels(4.8, 2)).toEqual([
+      "db0",
+      "db1",
+      "db2",
+      "db4",
+    ]);
+  });
+});