Prepare for public git: .gitignore, .env, sanitized configs

- Add .gitignore excluding .env, __pycache__, test_files (copyrighted PDFs),
  session logs, marker/ submodule, and other generated/private files
- Add .env with local config (gitignored); expand .env.example with all
  supported environment variables
- docker-compose.yml: all hardcoded values now use default pattern
- Containerfile: install marker-pdf from GitHub instead of local submodule;
  fix AMD_COMPUTE default to false; sanitize default OLLAMA_HOST
- Remove marker/ submodule from git tracking (keep local checkout via .gitignore)
- Remove session transcript and copyrighted ENISA PDFs from git tracking
- Sanitize local IPs in README, kubernetes deployment, deploy-podman.sh
- Fix hardcoded paths in convert_both.py and compare_conversions.py
- Update requirements.txt to reference GitHub instead of local --editable

.gitignore

@@ -0,0 +1,40 @@
+# ── Environment ──────────────────────────────────────
+.env
+
+# ── Python ───────────────────────────────────────────
+__pycache__/
+*.pyc
+*.pyo
+*.egg-info/
+dist/
+build/
+*.egg
+
+# ── Runtime output ───────────────────────────────────
+conversion_results/
+test_results/
+uploads/
+
+# ── Personal files ───────────────────────────────────
+session-*.md
+test_report_*.md
+*.log
+
+# ── IDE / editor ─────────────────────────────────────
+.opencode/
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# ── marker source (clone your own or install from pip) ─
+marker/
+
+# ── Test fixtures (copyrighted PDFs) ─────────────────
+test_files/
+*.pdf
+
+# ── OS ───────────────────────────────────────────────
+.DS_Store
+Thumbs.db