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/agile.py

@@ -0,0 +1,25 @@
+"""
+    pygments.lexers.agile
+    ~~~~~~~~~~~~~~~~~~~~~
+
+    Just export lexer classes previously contained in this module.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+# ruff: noqa: F401
+
+from pygments.lexers.lisp import SchemeLexer
+from pygments.lexers.jvm import IokeLexer, ClojureLexer
+from pygments.lexers.python import PythonLexer, PythonConsoleLexer, \
+    PythonTracebackLexer, Python3Lexer, Python3TracebackLexer, DgLexer
+from pygments.lexers.ruby import RubyLexer, RubyConsoleLexer, FancyLexer
+from pygments.lexers.perl import PerlLexer, Perl6Lexer
+from pygments.lexers.d import CrocLexer, MiniDLexer
+from pygments.lexers.iolang import IoLexer
+from pygments.lexers.tcl import TclLexer
+from pygments.lexers.factor import FactorLexer
+from pygments.lexers.scripting import LuaLexer, MoonScriptLexer
+
+__all__ = []