feat: Add Pythonic code checker tool

[nnennandukwe]

Summary

Add a new pythonic_check tool that detects non-idiomatic Python patterns and suggests Pythonic alternatives. This validates the shared core architecture and expands the code quality suite.

Parent Epic

Part of: Evolve into Python Code Quality MCP

Depends On

• Refactor shared Astroid utilities into core module

Patterns to Detect

Loop Anti-patterns

Anti-pattern	Pythonic Alternative
for i in range(len(items)):	for i, item in enumerate(items):
for key in d.keys():	for key in d:
for i in range(len(a)): ... a[i] ... b[i]	for x, y in zip(a, b):

Comparison Anti-patterns

Anti-pattern	Pythonic Alternative
if x == True: / if x == False:	if x: / if not x:
if x == None:	if x is None:
type(x) == SomeClass	isinstance(x, SomeClass)
if len(items) == 0:	if not items:

Resource Management

Anti-pattern	Pythonic Alternative
f = open(); ...; f.close()	with open() as f:
Manual lock acquire/release	with lock:

Collection Building

Anti-pattern	Pythonic Alternative
l = []; for x in y: l.append(f(x))	[f(x) for x in y]
d = {}; for x in y: d[k] = v	{k: v for x in y}
Loop with string concatenation	"".join(...)

Mutable Defaults

Anti-pattern	Pythonic Alternative
def foo(items=[]):	def foo(items=None): items = items or []
def foo(d={}):	def foo(d=None): d = d or {}

Other

Anti-pattern	Pythonic Alternative
if x: return True else: return False	return x / return bool(x)
Manual __enter__/__exit__ in simple cases	@contextmanager
lambda x: func(x)	Just func

MCP Tool Interface

{
  "name": "pythonic_check",
  "description": "Analyze Python code for non-idiomatic patterns and suggest Pythonic alternatives",
  "inputSchema": {
    "type": "object",
    "properties": {
      "file_path": {"type": "string"},
      "source_code": {"type": "string"}
    }
  }
}

Example Output

{
  "issues": [
    {
      "tool": "pythonic",
      "category": "non_idiomatic_loop",
      "severity": "warning",
      "message": "Use enumerate() instead of range(len())",
      "line": 42,
      "column": 4,
      "suggestion": "for i, item in enumerate(items):",
      "code_snippet": "for i in range(len(items)):"
    }
  ],
  "summary": {
    "total_issues": 5,
    "by_category": {
      "non_idiomatic_loop": 2,
      "mutable_default": 1,
      "comparison_to_none": 2
    }
  }
}

Implementation

1. Create src/workshop_mcp/tools/pythonic_check/
2. Define patterns in patterns.py
3. Implement checker using core Astroid utilities
4. Register tool in MCP server
5. Add tests in tests/test_pythonic_checker.py

Acceptance Criteria

• Detects at least 10 distinct anti-patterns
• Uses shared core utilities (not duplicated code)
• Provides actionable suggestions for each issue
• Comprehensive test coverage
• Registered as MCP tool