refactor(agents): drop ZWSP prefixes from agent display names

The sort shim from the previous commit enforces canonical core ordering at runtime, so ZWSP prefixes are no longer needed. Removing them eliminates the Bun.stringWidth vs terminal-width drift that broke the TUI status bar (#3259).

Drop AGENT_LIST_SORT_PREFIXES and getAgentRuntimeName from agent-display-names; switch all call sites to getAgentDisplayName. getAgentListDisplayName stays as a thin alias for external importers.

Keep stripInvisibleAgentCharacters and the ZWSP regex paths so legacy session state and configs from v3.14.0-v3.16.0 still resolve.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/agent-display-names.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "bun:test"
-import { AGENT_DISPLAY_NAMES, getAgentConfigKey, getAgentDisplayName, getAgentListDisplayName, normalizeAgentForPrompt, normalizeAgentForPromptKey } from "./agent-display-names"
+import { AGENT_DISPLAY_NAMES, getAgentConfigKey, getAgentDisplayName, getAgentListDisplayName, normalizeAgentForPrompt, normalizeAgentForPromptKey, stripAgentListSortPrefix } from "./agent-display-names"
 
 describe("getAgentDisplayName", () => {
   it("returns display name for lowercase config key (new format)", () => {
@@ -194,16 +194,26 @@ describe("getAgentConfigKey", () => {
 })
 
 describe("getAgentListDisplayName", () => {
-  it("applies invisible stable-sort prefixes to the core agent list", () => {
-    expect(getAgentListDisplayName("sisyphus")).toBe("\u200BSisyphus - Ultraworker")
-    expect(getAgentListDisplayName("hephaestus")).toBe("\u200B\u200BHephaestus - Deep Agent")
-    expect(getAgentListDisplayName("prometheus")).toBe("\u200B\u200B\u200BPrometheus - Plan Builder")
-    expect(getAgentListDisplayName("atlas")).toBe("\u200B\u200B\u200B\u200BAtlas - Plan Executor")
+  it("returns the canonical display name for the core agent list", () => {
+    expect(getAgentListDisplayName("sisyphus")).toBe("Sisyphus - Ultraworker")
+    expect(getAgentListDisplayName("hephaestus")).toBe("Hephaestus - Deep Agent")
+    expect(getAgentListDisplayName("prometheus")).toBe("Prometheus - Plan Builder")
+    expect(getAgentListDisplayName("atlas")).toBe("Atlas - Plan Executor")
   })
 
-  it("keeps non-core agents unprefixed for list display", () => {
+  it("keeps non-core agents unchanged for list display", () => {
     expect(getAgentListDisplayName("oracle")).toBe("oracle")
   })
+
+  it("is a thin alias for getAgentDisplayName", () => {
+    expect(getAgentListDisplayName("sisyphus")).toBe(getAgentDisplayName("sisyphus"))
+  })
+})
+
+describe("stripAgentListSortPrefix", () => {
+  it("strips legacy zero-width sort prefixes baked into v3.14.0–v3.16.0 sessions", () => {
+    expect(stripAgentListSortPrefix("\u200B\u200BHephaestus - Deep Agent")).toBe("Hephaestus - Deep Agent")
+  })
 })
 
 describe("normalizeAgentForPrompt", () => {