fix(extensions): always prefer vendored @fusion/pi-claude-cli over external installs

When users have an external pi-claude-cli (e.g. a global `npm install -g
pi-claude-cli`, or `npm:pi-claude-cli` in ~/.pi/agent/settings.json packages),
pi's extension discovery loaded the upstream copy and shadowed our fork. The
upstream has a once-and-lock MCP-config bug that throws "Extension runtime not
initialized" during early streamSimple calls and never recovers.

Adds reconcileClaudeCliPaths in @fusion/core, used by both the daemon's
extension assembly and the engine's per-session registerExtensionProviders, to
drop any path with a `pi-claude-cli` segment that isn't our vendored fork and
prepend the vendored path. Engine resolves the fork via require.resolve and
gracefully no-ops when it isn't reachable (e.g. embedded standalone usage).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/cli/src/commands/daemon.ts

@@ -21,6 +21,7 @@ import {
   GlobalSettingsStore,
   resolveGlobalDir,
   getEnabledPiExtensionPaths,
+  reconcileClaudeCliPaths,
 } from "@fusion/core";
 import type { AutomationRunResult, ScheduledTask } from "@fusion/core";
 import { createServer, GitHubClient, createSkillsAdapter, getProjectSettingsPath, loadTlsCredentialsFromEnv } from "@fusion/dashboard";
@@ -411,12 +412,17 @@ export async function runDaemon(opts: DaemonOptions = {}) {
       }
     })();
 
+    // Always prefer Fusion's vendored `@fusion/pi-claude-cli` over any
+    // external `pi-claude-cli` install. Drops shadowing externals (e.g. a
+    // global `npm install -g pi-claude-cli`) so the upstream's once-and-lock
+    // MCP-config bug can't poison sessions.
+    const reconciledExtensionPaths = reconcileClaudeCliPaths(
+      [...getEnabledPiExtensionPaths(cwd), ...packageExtensionPaths, ...claudeCliPaths],
+      claudeCliPaths[0] ?? null,
+    );
+
     const extensionsResult = await discoverAndLoadExtensions(
-      [
-        ...getEnabledPiExtensionPaths(cwd),
-        ...packageExtensionPaths,
-        ...claudeCliPaths,
-      ],
+      reconciledExtensionPaths,
       cwd,
       join(cwd, ".fusion", "disabled-auto-extension-discovery"),
     );