fix(terminal): drop native ARGV0 for bun-pty via env -u

bun-pty merges the OS environ into PTY children, so deleting ARGV0 from the
JS env object alone left the AppImage path in the shell. Wrap Linux PTY
spawns with env -u ARGV0, clear native ARGV0 under Bun via libc unsetenv,
and always clear process.env even when no login-shell snapshot exists.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/web/server/lib/inherited-env.js

@@ -9,6 +9,11 @@
  * See openchamber/openchamber#2588 and pingdotgg/t3code#2509.
  */
 
+import { createRequire } from 'node:module';
+import { existsSync } from 'node:fs';
+
+const LINUX_ENV_BINARIES = ['/usr/bin/env', '/bin/env'];
+
 /**
  * Remove AppImage `ARGV0` from a mutable env object (or `process.env`).
  * @param {NodeJS.ProcessEnv | Record<string, string | undefined> | null | undefined} env
@@ -21,3 +26,49 @@ export function stripAppImageArgv0Leak(env) {
   }
   return env;
 }
+
+/**
+ * Clear AppImage `ARGV0` from this process.
+ *
+ * Bun keeps a native environ that `bun-pty` inherits even after
+ * `delete process.env.ARGV0`. On Linux under Bun we also call libc `unsetenv`.
+ */
+export function clearAppImageArgv0FromProcessEnv() {
+  delete process.env.ARGV0;
+  if (process.platform !== 'linux' || typeof Bun === 'undefined') return;
+  try {
+    const require = createRequire(import.meta.url);
+    const { dlopen } = require('bun:ffi');
+    const libc = dlopen('libc.so.6', {
+      unsetenv: { args: ['cstring'], returns: 'i32' },
+    });
+    libc.symbols.unsetenv(Buffer.from('ARGV0\0'));
+  } catch {
+    // Node/Electron and environments without bun:ffi rely on explicit child envs.
+  }
+}
+
+/**
+ * Resolve a Linux PTY launch that drops native `ARGV0` before the shell starts.
+ *
+ * `bun-pty` merges the OS environ into the child, so deleting `ARGV0` from the
+ * JS env object alone is not enough. Wrapping with `env -u ARGV0` unsets it
+ * before execing the real shell. No-op on non-Linux platforms.
+ *
+ * @param {string} executable
+ * @param {string[]} args
+ * @returns {{ executable: string, args: string[] }}
+ */
+export function resolveLinuxPtyLaunch(executable, args = []) {
+  if (process.platform !== 'linux') {
+    return { executable, args };
+  }
+  const envBinary = LINUX_ENV_BINARIES.find((candidate) => existsSync(candidate));
+  if (!envBinary) {
+    return { executable, args };
+  }
+  return {
+    executable: envBinary,
+    args: ['-u', 'ARGV0', executable, ...args],
+  };
+}