fix(vibe): handle whitespace around = in .env keys to prevent duplicate entries

[SH20RAJ]

Summary

Fixes #1369.

mofa vibe fails to correctly update existing .env entries when the
file uses the KEY = value style (spaces around =). The old key is
kept and a new duplicate entry is appended, leading to
non-deterministic configuration and confusing multi-value .env files.

Root Cause

_save_vibe_config matched existing keys with:

stripped = line.strip()
if model and stripped.startswith("MOFA_VIBE_MODEL="):

startswith("KEY=") requires the = to be directly adjacent to the
key with no whitespace. A file containing

MOFA_VIBE_MODEL = gpt-4o-mini

is never matched, so the function falls through to the append path and
creates a duplicate:

MOFA_VIBE_MODEL = gpt-4o-mini   ← original (stale)
MOFA_VIBE_MODEL=gpt-4           ← new duplicate appended

The first value may win depending on which parser reads the file,
making the bug user-visible but non-deterministic.

Fix

Replace startswith() with a compiled regex that tolerates optional
leading whitespace and optional whitespace on both sides of =:

import re
_key_re = {k: re.compile(r"^\s*" + re.escape(k) + r"\s*=") for k in updated}

for i, line in enumerate(lines):
    if model and _key_re["MOFA_VIBE_MODEL"].match(line):
        lines[i] = f"MOFA_VIBE_MODEL={model}\n"   # update in-place
        updated["MOFA_VIBE_MODEL"] = True

This handles:

Format	Before	After
KEY=value	✅ matched	✅ matched
KEY = value	❌ missed → duplicate	✅ matched
KEY= value	❌ missed → duplicate	✅ matched
KEY = value	❌ missed → duplicate	✅ matched

Tests

Added mofa/tests/test_vibe_env_whitespace.py with five parameterised cases:

Test	Scenario
test_update_key_with_no_spaces	Baseline – standard KEY=value
test_update_key_with_spaces_around_equals	The exact #1369 regression
test_update_key_with_leading_whitespace	Leading-indent variant
test_new_key_appended_when_absent	Key absent → appended once
test_multiple_keys_all_updated	All four vibe keys with mixed styles

pytest mofa/tests/test_vibe_env_whitespace.py -v

All 5 tests pass.

Checklist

• Root cause identified
• Fix uses regex for robust whitespace tolerance
• 5 regression tests covering all whitespace variants
• No behaviour change for standard KEY=value format
• Fixes [Bug] fix: incorrect handling of whitespace in .env keys causes duplicate entries in vibe command. #1369