chore: ignore .venv/.claude/.vscode/.mcp.json, untrack committed pyc

.gitignore had `venv/` but the project's virtualenv is `.venv/`; add it plus
local-only agent/editor state so a `git add -A` can't sweep them in. Also stop
tracking four .pyc files committed before the __pycache__ ignore rule existed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -3,8 +3,14 @@ __pycache__/
 *.egg-info/
 .pytest_cache/
 venv/
+.venv/
 .worktrees/
 *.pdf
 
+# Local tooling / editor / agent state (not shared)
+.claude/
+.vscode/
+.mcp.json
+
 # Capture data (sniffs, sims, taginfo scans)
 data/