test: comprehensive test suite

Unit tests:
- test_security_boundaries.py: vault block, vault lock sentinel
- test_security_injection.py: all 4 injection categories, case-insensitive
- test_vault_rw.py: roundtrip, file permissions (chmod 400), no key in config
- test_config.py: schema roundtrip, no api_key field, chmod 600 on config.yaml
- test_memory_reader.py: list, read, sandboxing, context loading
- test_memory_writer.py: write, append, index update, traversal blocked, chmod 600
- test_providers.py: required fields, unique IDs, litellm prefix format
- test_renderer.py: key redaction for sk-ant-, sk-, AIza patterns

Security tests:
- test_vault_ai_isolation.py: 7 traversal patterns blocked via memory read/write
- test_path_traversal.py: 20+ traversal patterns — all rejected for read and write
- test_prompt_injection.py: 21-item corpus + 5 clean texts (no false positives)

Integration tests:
- test_lmstudio.py: live call to localhost:1234, streaming, full stack session,
  injection scan on real output (skips if LM Studio not running)

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

tests/unit/test_renderer.py

@@ -0,0 +1,36 @@
+from pyra.security.injection import redact_api_keys
+
+
+def test_anthropic_key_redacted():
+    text = "sk-ant-api03-abcdefghijklmnopqrstuvwxyz"
+    result = redact_api_keys(text)
+    assert "sk-ant-" not in result
+    assert "[REDACTED]" in result
+
+
+def test_openai_key_redacted():
+    text = "Key is sk-abcdefghijklmnopqrstu"
+    result = redact_api_keys(text)
+    assert "[REDACTED]" in result
+
+
+def test_google_key_redacted():
+    text = f"AIza{'B' * 35} is my key"
+    result = redact_api_keys(text)
+    assert "AIza" not in result
+    assert "[REDACTED]" in result
+
+
+def test_clean_text_unchanged():
+    text = "The answer is 42. No API keys here."
+    result = redact_api_keys(text)
+    assert result == text
+
+
+def test_multiple_keys_in_one_string():
+    text = (
+        f"First: sk-ant-{'x' * 20}, "
+        f"Second: sk-{'y' * 25}"
+    )
+    result = redact_api_keys(text)
+    assert result.count("[REDACTED]") >= 1