Move conversation_search.py out of repo, deduplicate .gitignore

- scripts/conversation_search.py was a personal dev tool (FTS5
  search over Claude conversation history). Moved to ~/dev-tools/.
  Has nothing to do with shorashim's spec or implementation.
- .DS_Store was already in .gitignore; deduplicated and removed
  the macOS metadata files from the working tree.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -3,48 +3,38 @@ l1/
 
 # External data sources — cloned at build time
 data/
-
 # Python
 __pycache__/
 *.pyc
 .venv/
 venv/
-
 # Secrets
 .env
-
 # OS
 .DS_Store
-
 # OpenCode local data (plugins, tools, skills)
 .opencode/
-
 # Editor
 *.swp
 *.swo
 *~
-
 # Erlang build artifacts
 sanhedrin/_build/
 sanhedrin/rebar3.crashdump
 erl_crash.dump
-
 # Haskell build artifacts
 shoresh-engine/dist-newstyle/
 shoresh-engine/.stack-work/
-
 # Elixir build artifacts
 vav_pipeline/_build/
 vav_pipeline/deps/
 talmudic_engine/_build/
 talmudic_engine/deps/
-
 # Python build artifacts
 korban_processor/.venv/
 korban_processor/__pycache__/
 **/__pycache__/
 **/*.pyc
-
 # Misc
 Untitled/
 aws-export/