test: add comprehensive coverage for cli, chat, renderer, dirs, install, paths

56 new tests covering previously untested modules:
- test_cli.py: memory write/read/append/list + plugin enable/disable + daemon stubs (via CliRunner)
- test_chat_history.py: ConversationHistory build_for_api, add_*/clear, _trim_to_budget
- test_chat_renderer.py: render_text_response return values, void render_* functions
- test_config_dirs.py: bootstrap idempotency, directory/template/vault/db creation
- test_plugin_install.py: list_bundled_plugins, read_manifest, install_bundled_plugin
- test_utils_paths.py: ensure_dir (nested, idempotent), safe_chmod

Total: 171 → 227 passing tests.

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

tests/unit/test_chat_renderer.py

@@ -0,0 +1,57 @@
+from pyra.security.injection import InjectionWarning
+
+
+def test_render_text_response_passthrough():
+    from pyra.chat.renderer import render_text_response
+    result = render_text_response("Hello world")
+    assert result == "Hello world"
+
+
+def test_render_text_response_redacts_api_key():
+    from pyra.chat.renderer import render_text_response
+    # anthropic-style key
+    result = render_text_response("key: sk-ant-api03-abcdefghijklmnopqrstuvwxyz123456")
+    assert "sk-ant" not in result
+    assert "[REDACTED]" in result
+
+
+def test_render_text_response_empty_string():
+    from pyra.chat.renderer import render_text_response
+    result = render_text_response("")
+    assert result == ""
+
+
+def test_render_text_response_whitespace_only():
+    from pyra.chat.renderer import render_text_response
+    result = render_text_response("   ")
+    assert result == "   "
+
+
+def test_render_error_no_exception():
+    from pyra.chat.renderer import render_error
+    render_error("Something went wrong")
+
+
+def test_render_info_no_exception():
+    from pyra.chat.renderer import render_info
+    render_info("Informational message")
+
+
+def test_render_system_no_exception():
+    from pyra.chat.renderer import render_system
+    render_system("System message")
+
+
+def test_render_injection_warning_no_exception():
+    from pyra.chat.renderer import render_injection_warning
+    warnings = [InjectionWarning(pattern_label="instruction-override", matched_text="ignore all")]
+    render_injection_warning(warnings)
+
+
+def test_render_injection_warning_multiple():
+    from pyra.chat.renderer import render_injection_warning
+    warnings = [
+        InjectionWarning(pattern_label="instruction-override", matched_text="ignore"),
+        InjectionWarning(pattern_label="jailbreak", matched_text="DAN mode"),
+    ]
+    render_injection_warning(warnings)