fix: create cortex config dir and restic password file during install

Previously the ~/.config/cortex/ directory and restic-password were only
created on the first backup run. Now install.py creates them eagerly so
the user can verify setup and back up the password immediately.

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

install.py

@@ -273,6 +273,27 @@ def setup_backup_timer(dry_run=False):
 
     ok("restic found")
 
+    # Create config dir and password file now so the user can back up the
+    # password immediately rather than waiting for the first scheduled run.
+    config_dir   = Path.home() / ".config" / "cortex"
+    password_file = config_dir / "restic-password"
+
+    if dry_run:
+        if password_file.exists():
+            ok(f"Password file exists: {password_file}")
+        else:
+            warn(f"Password file missing — would create: {password_file}")
+    else:
+        config_dir.mkdir(mode=0o700, parents=True, exist_ok=True)
+        if not password_file.exists():
+            import secrets
+            password_file.write_text(secrets.token_urlsafe(32) + "\n")
+            password_file.chmod(0o600)
+            ok(f"Password file created: {password_file}")
+            warn("Back this up somewhere safe — it's required to restore from backup")
+        else:
+            ok(f"Password file exists: {password_file}")
+
     svc_content = f"""\
 [Unit]
 Description=Cortex home backup (restic)