fix(tirith): detect Android/Termux as Linux ABI-compatible

In _detect_target(), platform.system() returns "Android" on Termux,
not "Linux". Without this change tirith's auto-installer skips
Android even though the Linux GNU binaries are ABI-compatible.

tools/tirith_security.py

@@ -186,9 +186,10 @@ def _detect_target() -> str | None:
     system = platform.system()
     machine = platform.machine().lower()
 
+    # Android (Termux) is ABI-compatible with Linux — reuse Linux binaries.
     if system == "Darwin":
         plat = "apple-darwin"
-    elif system == "Linux":
+    elif system in ("Linux", "Android"):
         plat = "unknown-linux-gnu"
     else:
         return None