fix(providers): add polling timeouts, fix credential parsing, validate dependencies

- GitHub Actions: max 4-hour polling with clear timeout error including run URL
- GitLab CI: max 4-hour polling with clear timeout error including pipeline URL
- Remote PowerShell: fix credential split to preserve passwords with colons
  (split on first colon only instead of all colons)
- Remote PowerShell: throw clear error when credential format is invalid
- Ansible: validate ansible-playbook binary exists in setupWorkflow
  (separate from ansible --version check)
- All timeout errors use core.error() for GitHub Actions annotation visibility

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

src/model/orchestrator/providers/remote-powershell/index.ts

@@ -148,11 +148,17 @@ class RemotePowershellProvider implements ProviderInterface {
     }
 
     // WinRM (default)
-    const credentialPart = this.credential
-      ? `-Credential (New-Object PSCredential('${this.credential.split(':')[0]}', (ConvertTo-SecureString '${
-          this.credential.split(':')[1]
-        }' -AsPlainText -Force)))`
-      : '';
+    // Split on the FIRST colon only — passwords may contain colons
+    let credentialPart = '';
+    if (this.credential) {
+      const colonIndex = this.credential.indexOf(':');
+      if (colonIndex === -1) {
+        throw new Error('remotePowershellCredential must be in "username:password" format (no colon found)');
+      }
+      const user = this.credential.substring(0, colonIndex);
+      const pass = this.credential.substring(colonIndex + 1);
+      credentialPart = `-Credential (New-Object PSCredential('${user}', (ConvertTo-SecureString '${pass}' -AsPlainText -Force)))`;
+    }
 
     return `pwsh -NoProfile -NonInteractive -Command "Invoke-Command -ComputerName '${this.host}' ${credentialPart} -ScriptBlock { ${escapedScript} }"`;
   }