fix(skills): deduplicate slash commands by skillName across all interfaces

Move skill-command deduplication by skillName from the Discord-only
`dedupeSkillCommandsForDiscord` into `listSkillCommandsForAgents` so
every interface (TUI, Slack, text) consistently sees a clean command
list without platform-specific workarounds.

When multiple agents share a skill with the same name the old code
emitted `github` + `github_2` and relied on Discord to collapse them.
Now `listSkillCommandsForAgents` returns only the first registration
per skillName, and the Discord-specific wrapper is removed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/auto-reply/skill-commands.ts

@@ -46,6 +46,26 @@ export function listSkillCommandsForWorkspace(params: {
   });
 }
 
+// Deduplicate skill commands by skillName, keeping the first registration.
+// When multiple agents have a skill with the same name (e.g. one with a
+// workspace override and one from bundled), the suffix-renamed entries
+// (github_2, github_3…) are dropped so every interface sees a clean list.
+function dedupeBySkillName(commands: SkillCommandSpec[]): SkillCommandSpec[] {
+  const seen = new Set<string>();
+  const out: SkillCommandSpec[] = [];
+  for (const cmd of commands) {
+    const key = cmd.skillName.trim().toLowerCase();
+    if (key && seen.has(key)) {
+      continue;
+    }
+    if (key) {
+      seen.add(key);
+    }
+    out.push(cmd);
+  }
+  return out;
+}
+
 export function listSkillCommandsForAgents(params: {
   cfg: OpenClawConfig;
   agentIds?: string[];
@@ -109,9 +129,16 @@ export function listSkillCommandsForAgents(params: {
       entries.push(command);
     }
   }
-  return entries;
+  // Dedupe by skillName across workspaces so every interface (Discord, TUI,
+  // Slack, text) sees a consistent command list without platform-specific
+  // workarounds.
+  return dedupeBySkillName(entries);
 }
 
+export const __testing = {
+  dedupeBySkillName,
+};
+
 function normalizeSkillCommandLookup(value: string): string {
   return value
     .trim()