fix(agents): strip ZWSP ordering prefixes in session state, config lookups, and override protection

Prevent ZWSP sort prefixes from leaking into stored agent names, config
key lookups, and override-protection normalization. Ensures prefixed
list-display names resolve correctly throughout the pipeline.

🤖 Generated with [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode) assistance

src/features/claude-code-session-state/state.test.ts

@@ -37,6 +37,18 @@ describe("claude-code-session-state", () => {
       expect(getSessionAgent(sessionID)).toBe(agent)
     })
 
+    test("should strip zero-width ordering prefixes before storing agent for session", () => {
+      // given
+      const sessionID = "test-session-prefixed"
+      const agent = "\u200B\u200B\u200BPrometheus (Plan Builder)"
+
+      // when
+      setSessionAgent(sessionID, agent)
+
+      // then
+      expect(getSessionAgent(sessionID)).toBe("Prometheus (Plan Builder)")
+    })
+
     test("should NOT overwrite existing agent (first-write wins)", () => {
       // given
       const sessionID = "test-session-1"
@@ -69,6 +81,18 @@ describe("claude-code-session-state", () => {
       // then
       expect(getSessionAgent(sessionID)).toBe("sisyphus")
     })
+
+    test("should strip zero-width ordering prefixes when overwriting existing agent", () => {
+      // given
+      const sessionID = "test-session-prefixed-update"
+      setSessionAgent(sessionID, "sisyphus")
+
+      // when
+      updateSessionAgent(sessionID, "\u200B\u200BHephaestus (Deep Agent)")
+
+      // then
+      expect(getSessionAgent(sessionID)).toBe("Hephaestus (Deep Agent)")
+    })
   })
 
   describe("clearSessionAgent", () => {