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/bqn.py

@@ -0,0 +1,112 @@
+"""
+    pygments.lexers.bqn
+    ~~~~~~~~~~~~~~~~~~~
+
+    Lexer for BQN.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.lexer import RegexLexer
+from pygments.token import Comment, Operator, Keyword, Name, String, \
+    Number, Punctuation, Whitespace
+
+__all__ = ['BQNLexer']
+
+
+class BQNLexer(RegexLexer):
+    """
+    A simple BQN lexer.
+    """
+    name = 'BQN'
+    url = 'https://mlochbaum.github.io/BQN/index.html'
+    aliases = ['bqn']
+    filenames = ['*.bqn']
+    mimetypes = []
+    version_added = '2.16'
+
+    # An inter_word_char. Necessary because \w matches all alphanumeric
+    # Unicode characters, including ones (e.g., 𝕊) that BQN treats special.
+    _iwc = r'((?=[^𝕎𝕏𝔽𝔾𝕊𝕨𝕩𝕗𝕘𝕤𝕣])\w)'
+
+    tokens = {
+        'root': [
+            # Whitespace
+            # ==========
+            (r'\s+', Whitespace),
+            #
+            # Comment
+            # =======
+            # '#' is a comment that continues to the end of the line
+            (r'#.*$', Comment.Single),
+            #
+            # Strings
+            # =======
+            (r'\'((\'\')|[^\'])*\'', String.Single),
+            (r'"(("")|[^"])*"', String.Double),
+            #
+            # Null Character
+            # ==============
+            # Literal representation of the null character
+            (r'@', String.Symbol),
+            #
+            # Punctuation
+            # ===========
+            # This token type is used for diamond, commas
+            # and  array and list brackets and strand syntax
+            (r'[\.⋄,\[\]⟨⟩‿]', Punctuation),
+            #
+            # Expression Grouping
+            # ===================
+            # Since this token type is important in BQN, it is not included in
+            # the punctuation token type but rather in the following one
+            (r'[\(\)]', String.Regex),
+            #
+            # Numbers
+            # =======
+            # Includes the numeric literals and the Nothing character
+            (r'¯?[0-9](([0-9]|_)*\.?([0-9]|_)+|([0-9]|_)*)([Ee][¯]?([0-9]|_)+)?|¯|∞|π|·', Number),
+            #
+            # Variables
+            # =========
+            (r'[a-z]' + _iwc + r'*', Name.Variable),
+            #
+            # 2-Modifiers
+            # ===========
+            # Needs to come before the 1-modifiers due to _𝕣 and _𝕣_
+            (r'[∘○⊸⟜⌾⊘◶⎉⚇⍟⎊]', Name.Property),
+            (r'_(𝕣|[a-zA-Z0-9]+)_', Name.Property),
+            #
+            # 1-Modifiers
+            # ===========
+            (r'[˙˜˘¨⌜⁼´˝`𝕣]', Name.Attribute),
+            (r'_(𝕣|[a-zA-Z0-9]+)', Name.Attribute),
+            #
+            # Functions
+            # =========
+            # The monadic or dyadic function primitives and function
+            # operands and arguments, along with function self-reference
+            (r'[+\-×÷\⋆√⌊⌈∧∨¬|≤<>≥=≠≡≢⊣⊢⥊∾≍⋈↑↓↕«»⌽⍉/⍋⍒⊏⊑⊐⊒∊⍷⊔!𝕎𝕏𝔽𝔾𝕊]',
+             Operator),
+            (r'[A-Z]' + _iwc + r'*|•' + _iwc + r'+', Operator),
+            #
+            # Constant
+            # ========
+            (r'˙', Name.Constant),
+            #
+            # Define/Export/Change
+            # ====================
+            (r'[←↩⇐]', Keyword.Declaration),
+            #
+            # Blocks
+            # ======
+            (r'[{}]', Keyword.Type),
+            #
+            # Extra characters
+            # ================
+            (r'[;:?𝕨𝕩𝕗𝕘𝕤]', Name.Entity),
+            #
+
+        ],
+    }