fix(desktop): fix broken install links, wrong adapter package, and hermit env leak

Replace window.open() with <a target="_blank"> for "View instructions"
links — Tauri blocks window.open but handles anchor tags correctly.

Fix Claude Code adapter install command: the package is
@agentclientprotocol/claude-agent-acp (not @anthropic-ai/claude-agent-acp
which doesn't exist on npm).

Strip NPM_CONFIG_PREFIX, NPM_CONFIG_CACHE, and COREPACK_HOME from the
install subprocess environment so npm uses the user's normal registry
rather than inheriting hermit's project-local Artifactory proxy config.

desktop/src-tauri/src/commands/agent_discovery.rs

@@ -105,6 +105,12 @@ fn run_install_command(step: &str, command: &str) -> InstallStepResult {
     let mut cmd = std::process::Command::new(shell);
     cmd.args(["-l", "-c", command]);
 
+    // Strip hermit env vars so npm/node use the user's normal registry and
+    // global prefix rather than the project-local hermit-managed paths.
+    cmd.env_remove("NPM_CONFIG_PREFIX");
+    cmd.env_remove("NPM_CONFIG_CACHE");
+    cmd.env_remove("COREPACK_HOME");
+
     if let Some(ref path) = shell_path {
         cmd.env("PATH", path);
     }

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -82,8 +82,8 @@ const KNOWN_ACP_PROVIDERS: &[KnownAcpProvider] = &[
         mcp_hooks: false,
         underlying_cli: Some("claude"),
         cli_install_commands: &["npm install -g @anthropic-ai/claude-code"],
-        adapter_install_commands: &["npm install -g @anthropic-ai/claude-agent-acp"],
-        install_instructions_url: "https://www.npmjs.com/package/@anthropic-ai/claude-agent-acp",
+        adapter_install_commands: &["npm install -g @agentclientprotocol/claude-agent-acp"],
+        install_instructions_url: "https://github.com/agentclientprotocol/claude-agent-acp",
         install_hint: "Install the Claude Code ACP adapter via npm.",
     },
     KnownAcpProvider {

desktop/src/features/settings/ui/DoctorSettingsPanel.tsx

@@ -60,14 +60,15 @@ function InstallActions({
           {isInstalling ? "Installing..." : "Install"}
         </Button>
       ) : null}
-      <button
+      <a
         className="inline-flex items-center gap-1 text-xs text-muted-foreground underline-offset-2 hover:text-foreground hover:underline"
-        onClick={() => window.open(provider.installInstructionsUrl, "_blank")}
-        type="button"
+        href={provider.installInstructionsUrl}
+        rel="noopener noreferrer"
+        target="_blank"
       >
         <ExternalLink className="h-3 w-3" />
         View instructions
-      </button>
+      </a>
     </div>
   );
 }