fix(agent-names): use HTTP-header-safe display names and config keys for API calls (#3138)

Display names with parentheses like 'Atlas (Plan Executor)' cause HTTP
header validation errors in x-opencode-agent-name. This was blocking
Atlas/Prometheus from working via /start-work and auto-retry.

Changes:
- Display names: parens -> dashes ('Atlas - Plan Executor')
- Hooks (start-work, no-hephaestus-non-gpt, no-sisyphus-gpt): use
  config keys ('atlas', 'sisyphus', 'hephaestus') for agent API fields
- auto-retry: use config key instead of display name for promptAsync
- agent-override-protection: handle dash-suffix normalization
- Updated all test expectations to match new format

Closes #3138

src/hooks/no-hephaestus-non-gpt/hook.ts

@@ -54,11 +54,11 @@ export function createNoHephaestusNonGptHook(
         if (allowNonGptModel) {
           return
         }
-        input.agent = SISYPHUS_DISPLAY
+        input.agent = "sisyphus"
         if (output?.message) {
-          output.message.agent = SISYPHUS_DISPLAY
+          output.message.agent = "sisyphus"
         }
-        updateSessionAgent(input.sessionID, SISYPHUS_DISPLAY)
+        updateSessionAgent(input.sessionID, "sisyphus")
       }
     },
   }

src/hooks/no-hephaestus-non-gpt/index.test.ts

@@ -40,8 +40,8 @@ describe("no-hephaestus-non-gpt hook", () => {
 
     // then - toast is shown and agent is switched to sisyphus
     expect(showToast).toHaveBeenCalledTimes(2)
-    expect(output1.message.agent).toBe(SISYPHUS_DISPLAY)
-    expect(output2.message.agent).toBe(SISYPHUS_DISPLAY)
+    expect(output1.message.agent).toBe("sisyphus")
+    expect(output2.message.agent).toBe("sisyphus")
     expect(showToast.mock.calls[0]?.[0]).toMatchObject({
       body: {
         title: "NEVER Use Hephaestus with Non-GPT",
@@ -141,6 +141,6 @@ describe("no-hephaestus-non-gpt hook", () => {
 
     // then - toast shown via session-agent fallback, switched to sisyphus
     expect(showToast).toHaveBeenCalledTimes(1)
-    expect(output.message.agent).toBe(SISYPHUS_DISPLAY)
+    expect(output.message.agent).toBe("sisyphus")
   })
 })