test: add comprehensive unit tests and fix bare excepts

- Added comprehensive unit test suite covering AI, core, plugins, completion, API, and hooks using pytest.
- Replaced bare 'except:' clauses across the codebase with specific exception handling (e.g., ValueError, KeyError, OSError) to prevent swallowing system exit calls.
- Fixed Python 3.8+ AST compatibility in plugins.py (support for ast.Constant).
- Removed deprecated pkg_resources import from __init__.py.
- Fixed missing 'printer' import in configfile.py that caused NameErrors during save failures.

connpy/tests/test_printer.py

@@ -0,0 +1,50 @@
+"""Tests for connpy.printer module."""
+import sys
+from io import StringIO
+from connpy import printer
+
+
+class TestPrinter:
+    def test_info_output(self, capsys):
+        printer.info("hello world")
+        captured = capsys.readouterr()
+        assert "[i] hello world" in captured.out
+
+    def test_success_output(self, capsys):
+        printer.success("done")
+        captured = capsys.readouterr()
+        assert "[✓] done" in captured.out
+
+    def test_warning_output(self, capsys):
+        printer.warning("careful")
+        captured = capsys.readouterr()
+        assert "[!] careful" in captured.out
+
+    def test_error_output(self, capsys):
+        printer.error("failed")
+        captured = capsys.readouterr()
+        assert "[✗] failed" in captured.err
+
+    def test_debug_output(self, capsys):
+        printer.debug("debug info")
+        captured = capsys.readouterr()
+        assert "[d] debug info" in captured.out
+
+    def test_start_output(self, capsys):
+        printer.start("starting")
+        captured = capsys.readouterr()
+        assert "[+] starting" in captured.out
+
+    def test_custom_output(self, capsys):
+        printer.custom("TAG", "custom message")
+        captured = capsys.readouterr()
+        assert "[TAG] custom message" in captured.out
+
+    def test_multiline_indentation(self, capsys):
+        printer.info("line1\nline2\nline3")
+        captured = capsys.readouterr()
+        lines = captured.out.strip().split("\n")
+        assert lines[0] == "[i] line1"
+        # Second line should be indented by len("[i] ") = 4 chars
+        assert lines[1].startswith("    line2")
+        assert lines[2].startswith("    line3")