HOTFIX: Remove broad preposition/nasb regex rules — caused Hallucination 0%, +38 FP

The regex patterns (ون→ين after prepositions, ون→وا after nasb particles)
were matching correct text everywhere. CamelTools-based rules handle these
with POS-tag awareness. Keep only narrow five-nouns patterns.

src/nlp/grammar/grammar_rules.py

@@ -351,13 +351,10 @@ class ArabicGrammarGuard:
         text = re.sub(r'\b([وف]?[بل])(أبوك|أباك|أخوك|أخاك|ذو|ذا)\b',
                       lambda m: f"{m.group(1)}{m.group(2).replace('و', 'ي').replace('ا', 'ي')}", text)
 
-        # ── NEW: Preposition + ون→ين case (في المهندسون→المهندسين) ──
-        text = re.sub(r'\b([وف]?(?:في|من|إلى|على|عن|حتى))\s+([أ-ي]{4,})(ون|ان)\b', r'\1 \2ين', text)
-        text = re.sub(r'\b([وف]?[بلكف])ال([أ-ي]{4,})(ون|ان)\b', r'\1ال\2ين', text)
-        text = re.sub(r'\b([وف]?ل)([أ-ي]{4,})(ون|ان)\b', r'\1\2ين', text)
-
-        # ── NEW: Nasb/Jazm ون→وا (لن يذهبون→يذهبوا) ──
-        text = re.sub(r'\b(لن|لم|كي|لكي|حتى|أن)\s+([أ-ي]+)(ون)\b', r'\1 \2وا', text)
+        # NOTE: Broad preposition case (ون→ين) and nasb (ون→وا) regex rules
+        # were REMOVED because they caused massive overcorrection on correct text.
+        # These patterns are handled by CamelTools-based rules (fix_prepositions_advanced,
+        # fix_verbs_nasb_and_jazm) which have POS-tag awareness.
 
         return text