feat(phase1): add image storage utilities

- Create backend/services/image_storage.py with 4 core functions:
  - sanitize_filename(): remove unsafe chars, limit to 255 chars, convert to lowercase
  - get_unique_filename(): handle collisions with UUID suffix (format: {name}_{uuid8}_{variant}.jpg)
  - ensure_image_directories(): create /images/ root and category subdirs on startup
  - save_image(): save bytes to /images/{category}/{filename}, returns relative path
- Create comprehensive test suite (22 tests) covering all functionality
- Integrate ensure_image_directories() into FastAPI startup event
- Directory structure: /images/{category}/{filename}
- Collision handling: auto-suffix with UUID if filename exists
- All tests passing, pathlib.Path for safe operations

venv/lib/python3.12/site-packages/pygments/lexers/roboconf.py

@@ -0,0 +1,81 @@
+"""
+    pygments.lexers.roboconf
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Lexers for Roboconf DSL.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.lexer import RegexLexer, words, re
+from pygments.token import Text, Operator, Keyword, Name, Comment
+
+__all__ = ['RoboconfGraphLexer', 'RoboconfInstancesLexer']
+
+
+class RoboconfGraphLexer(RegexLexer):
+    """
+    Lexer for Roboconf graph files.
+    """
+    name = 'Roboconf Graph'
+    aliases = ['roboconf-graph']
+    filenames = ['*.graph']
+    url = 'https://roboconf.github.io/en/user-guide/graph-definition.html'
+    version_added = '2.1'
+
+    flags = re.IGNORECASE | re.MULTILINE
+    tokens = {
+        'root': [
+            # Skip white spaces
+            (r'\s+', Text),
+
+            # There is one operator
+            (r'=', Operator),
+
+            # Keywords
+            (words(('facet', 'import'), suffix=r'\s*\b', prefix=r'\b'), Keyword),
+            (words((
+                'installer', 'extends', 'exports', 'imports', 'facets',
+                'children'), suffix=r'\s*:?', prefix=r'\b'), Name),
+
+            # Comments
+            (r'#.*\n', Comment),
+
+            # Default
+            (r'[^#]', Text),
+            (r'.*\n', Text)
+        ]
+    }
+
+
+class RoboconfInstancesLexer(RegexLexer):
+    """
+    Lexer for Roboconf instances files.
+    """
+    name = 'Roboconf Instances'
+    aliases = ['roboconf-instances']
+    filenames = ['*.instances']
+    url = 'https://roboconf.github.io'
+    version_added = '2.1'
+
+    flags = re.IGNORECASE | re.MULTILINE
+    tokens = {
+        'root': [
+
+            # Skip white spaces
+            (r'\s+', Text),
+
+            # Keywords
+            (words(('instance of', 'import'), suffix=r'\s*\b', prefix=r'\b'), Keyword),
+            (words(('name', 'count'), suffix=r's*:?', prefix=r'\b'), Name),
+            (r'\s*[\w.-]+\s*:', Name),
+
+            # Comments
+            (r'#.*\n', Comment),
+
+            # Default
+            (r'[^#]', Text),
+            (r'.*\n', Text)
+        ]
+    }