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/styles/vim.py

@@ -0,0 +1,67 @@
+"""
+    pygments.styles.vim
+    ~~~~~~~~~~~~~~~~~~~
+
+    A highlighting style for Pygments, inspired by vim.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.style import Style
+from pygments.token import Keyword, Name, Comment, String, Error, \
+     Number, Operator, Generic, Whitespace, Token
+
+
+__all__ = ['VimStyle']
+
+
+class VimStyle(Style):
+    """
+    Styles somewhat like vim 7.0
+    """
+
+    name = 'vim'
+    
+    background_color = "#000000"
+    highlight_color = "#222222"
+
+    styles = {
+        Token:                     "#cccccc",
+        Whitespace:                "",
+        Comment:                   "#000080",
+        Comment.Preproc:           "",
+        Comment.Special:           "bold #cd0000",
+
+        Keyword:                   "#cdcd00",
+        Keyword.Declaration:       "#00cd00",
+        Keyword.Namespace:         "#cd00cd",
+        Keyword.Pseudo:            "",
+        Keyword.Type:              "#00cd00",
+
+        Operator:                  "#3399cc",
+        Operator.Word:             "#cdcd00",
+
+        Name:                      "",
+        Name.Class:                "#00cdcd",
+        Name.Builtin:              "#cd00cd",
+        Name.Exception:            "bold #666699",
+        Name.Variable:             "#00cdcd",
+
+        String:                    "#cd0000",
+        Number:                    "#cd00cd",
+
+        Generic.Heading:           "bold #000080",
+        Generic.Subheading:        "bold #800080",
+        Generic.Deleted:           "#cd0000",
+        Generic.Inserted:          "#00cd00",
+        Generic.Error:             "#FF0000",
+        Generic.Emph:              "italic",
+        Generic.Strong:            "bold",
+        Generic.EmphStrong:        "bold italic",
+        Generic.Prompt:            "bold #000080",
+        Generic.Output:            "#888",
+        Generic.Traceback:         "#04D",
+
+        Error:                     "border:#FF0000"
+    }