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/shared/agent-display-names.ts

@@ -4,15 +4,15 @@
  * Display names include suffixes for UI/logs (e.g., "Sisyphus (Ultraworker)").
  */
 export const AGENT_DISPLAY_NAMES: Record<string, string> = {
-  sisyphus: "Sisyphus (Ultraworker)",
-  hephaestus: "Hephaestus (Deep Agent)",
-  prometheus: "Prometheus (Plan Builder)",
-  atlas: "Atlas (Plan Executor)",
+  sisyphus: "Sisyphus - Ultraworker",
+  hephaestus: "Hephaestus - Deep Agent",
+  prometheus: "Prometheus - Plan Builder",
+  atlas: "Atlas - Plan Executor",
   "sisyphus-junior": "Sisyphus-Junior",
-  metis: "Metis (Plan Consultant)",
-  momus: "Momus (Plan Critic)",
-  athena: "Athena (Council)",
-  "athena-junior": "Athena-Junior (Council)",
+  metis: "Metis - Plan Consultant",
+  momus: "Momus - Plan Critic",
+  athena: "Athena - Council",
+  "athena-junior": "Athena-Junior - Council",
   oracle: "oracle",
   librarian: "librarian",
   explore: "explore",