add functional tests for 7 major SDKs (Python, Go, JS, Ruby, PHP, Java, Rust)

Each test file covers 10 real API tests matching the C SDK reference:
health_check, validate_keys, get_languages, execute, execute_error,
session_list, session_lifecycle, service_list, snapshot_list, image_list.

All tests skip cleanly without credentials. No soft passes.
Updated all 7 Makefiles to run dedicated functional test files.

clients/python/sync/tests/test_functional.py

@@ -0,0 +1,118 @@
+# This is free software for the public good of a permacomputer hosted at
+# permacomputer.com, an always-on computer by the people, for the people.
+# One which is durable, easy to repair, & distributed like tap water
+# for machine learning intelligence.
+#
+# The permacomputer is community-owned infrastructure optimized around
+# four values:
+#
+#   TRUTH      First principles, math & science, open source code freely distributed
+#   FREEDOM    Voluntary partnerships, freedom from tyranny & corporate control
+#   HARMONY    Minimal waste, self-renewing systems with diverse thriving connections
+#   LOVE       Be yourself without hurting others, cooperation through natural law
+#
+# This software contributes to that vision by enabling code execution across 42+ programming languages through a unified interface, accessible to all.
+# Code is seeds to sprout on any abandoned technology.
+
+"""
+UN Python SDK - Functional Tests
+
+Tests library functions against real API.
+Requires: UNSANDBOX_PUBLIC_KEY, UNSANDBOX_SECRET_KEY
+
+Usage:
+    cd clients/python/sync && PYTHONPATH=src pytest tests/test_functional.py -v
+"""
+
+import os
+import sys
+import pytest
+
+# Import SDK functions
+from un import (
+    execute_code,
+    get_languages,
+    list_sessions,
+    list_services,
+    list_snapshots,
+    list_images,
+    validate_keys,
+    health_check,
+)
+
+
+# Skip all tests if no credentials
+pytestmark = pytest.mark.skipif(
+    not os.environ.get("UNSANDBOX_PUBLIC_KEY") or not os.environ.get("UNSANDBOX_SECRET_KEY"),
+    reason="UNSANDBOX_PUBLIC_KEY and UNSANDBOX_SECRET_KEY required",
+)
+
+
+class TestFunctional:
+    """Functional tests against real API (matches C SDK test_functional.c)"""
+
+    def test_health_check(self):
+        """API health check returns boolean"""
+        result = health_check()
+        assert isinstance(result, bool)
+
+    def test_validate_keys(self):
+        """API keys validate successfully"""
+        info = validate_keys()
+        assert isinstance(info, dict)
+        assert "valid" in info
+        assert info["valid"] is True
+
+    def test_get_languages(self):
+        """Languages endpoint returns list with python"""
+        langs = get_languages()
+        assert isinstance(langs, list)
+        assert len(langs) > 0
+        assert "python" in langs
+
+    def test_execute(self):
+        """Execute python code and verify stdout"""
+        result = execute_code("python", "print('hello from Python SDK')")
+        assert isinstance(result, dict)
+        assert result.get("success") is True
+        assert "hello from Python SDK" in result.get("stdout", "")
+        assert result.get("exit_code") == 0
+
+    def test_execute_error(self):
+        """Execute code that exits with error"""
+        result = execute_code("python", "import sys; sys.exit(1)")
+        assert isinstance(result, dict)
+        assert result.get("success") is False
+        assert result.get("exit_code") == 1
+
+    def test_session_list(self):
+        """List sessions returns list"""
+        sessions = list_sessions()
+        assert isinstance(sessions, list)
+
+    def test_session_lifecycle(self):
+        """Create and destroy a session"""
+        from un import create_session, delete_session
+
+        session = create_session("python")
+        assert isinstance(session, dict)
+        assert "id" in session
+        session_id = session["id"]
+
+        destroyed = delete_session(session_id)
+        assert destroyed is not None
+
+    def test_service_list(self):
+        """List services returns list"""
+        services = list_services()
+        assert isinstance(services, list)
+
+    def test_snapshot_list(self):
+        """List snapshots returns list"""
+        snapshots = list_snapshots()
+        assert isinstance(snapshots, list)
+
+    def test_image_list(self):
+        """List images returns list"""
+        images = list_images()
+        assert isinstance(images, list)