fix(config): Standardize line length to 120 characters across all tools

Fixed line length inconsistency issue identified in quality assessment.

Problem:
- pyproject.toml configured for 100 characters
- .pre-commit-config.yaml configured for 120 characters
- scripts/quality-check.sh configured for 120 characters
- Caused inconsistent formatting between tools

Solution:
Updated pyproject.toml to use 120 characters to match other tooling:
- [tool.black] line-length: 100 → 120
- [tool.isort] line_length: 100 → 120

Rationale for 120 characters:
✅ Matches pre-commit hooks (.pre-commit-config.yaml)
✅ Matches quality-check.sh script
✅ 376 backend files already formatted to 120 chars (commit 54a7841)
✅ More readable on modern wide screens
✅ Industry best practice for Python (PEP 8 allows up to 99, but
   Black recommends 88-120 for modern development)

Impact:
- All formatting tools now use consistent 120-char line length
- No more conflicts between local formatting and CI checks
- Developers get consistent results across all quality tools

Verified:
- pyproject.toml: 120 ✓
- .pre-commit-config.yaml: 120 ✓
- scripts/quality-check.sh: 120 ✓

Closes: Critical Gaps Section 2 (Line Length Inconsistency)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: remyluslosius

pyproject.toml

@@ -27,7 +27,7 @@ python_classes = ["Test*"]
 python_functions = ["test_*", "validate_*"]
 markers = [
     "unit: Unit tests for individual components",
-    "integration: Integration tests for component interactions", 
+    "integration: Integration tests for component interactions",
     "performance: Performance and load tests",
     "security: Security and compliance validation tests",
     "scap: SCAP scanning and processing tests",
@@ -50,7 +50,7 @@ filterwarnings = [
 source = ["app"]
 omit = [
     "*/tests/*",
-    "*/validation/*", 
+    "*/validation/*",
     "*/migrations/*",
     "*/venv/*",
     "*/node_modules/*",
@@ -63,14 +63,14 @@ exclude_lines = [
     "pragma: no cover",
     "def __repr__",
     "raise AssertionError",
-    "raise NotImplementedError", 
+    "raise NotImplementedError",
     "if __name__ == .__main__.:",
     "class .*\\bProtocol\\):",
     "@(abc\\.)?abstractmethod",
 ]
 
 [tool.black]
-line-length = 100
+line-length = 120
 target-version = ['py39', 'py310', 'py311']
 include = '\.pyi?$'
 extend-exclude = '''
@@ -91,7 +91,7 @@ extend-exclude = '''
 
 [tool.isort]
 profile = "black"
-line_length = 100
+line_length = 120
 multi_line_output = 3
 include_trailing_comma = true
 force_grid_wrap = 0
@@ -113,4 +113,4 @@ warn_redundant_casts = true
 warn_return_any = true
 warn_unreachable = true
 warn_unused_configs = true
-warn_unused_ignores = true
+warn_unused_ignores = true