feat: add word_freq.py CLI tool

[raajkumars]

Relates to http://localhost:3000/agentflow/agentflow/issues/4

Summary

Adds word_freq.py, a stdlib-only CLI that reads a text file and prints the top-N most frequent words (case-insensitive, punctuation stripped). Refines the existing implementation on main: consolidates word counting into a single word_freq() function, expands the word-character regex to include apostrophes, and tightens argument help strings.

Files changed

• word_freq.py: consolidated implementation (~45 lines)

Tests

Smoke-tested manually:

• Basic top-10 output: pass
• --top 3 override: pass
• Missing file → clear error message: pass
• --top 0 → argparse error (N must be >= 1): pass

Deviations from plan

None.

Follow-ups

None.

[raajkumars]

Reviewer note (self-authored — cannot formally approve):

Code looks correct. One nit for the next person or the author to address:

• word_freq.py:25 — re.findall(r"[a-zA-Z']+", text.lower()): the [A-Z] range is dead code because .lower() has already been applied. Suggest r"[a-z']+" for clarity. Non-blocking.

Everything else (consolidated word_freq(), sys.exit(msg) idiom, error messages) is idiomatic and clean. Needs an external reviewer to formally approve.