chore: improve agent readiness — AGENTS.md, dependabot, CODEOWNERS, labels

- Add AGENTS.md with build commands, project structure, conventions
- Add .github/dependabot.yml for automated pip + actions updates
- Add .github/CODEOWNERS for review routing
- Expand .gitignore (.env, .DS_Store, IDE configs, coverage, venvs)
- Add C901 complexity rule to ruff (max-complexity=25, benchmarks excluded)
- Add --durations=10 to pytest CI for test performance tracking
- Add docs/schema.sql for knowledge graph schema documentation
- Created P0-P3 priority + area/* + security/performance/docs labels

.github/CODEOWNERS

@@ -0,0 +1,13 @@
+# Default owners for everything
+* @milla-jovovich @bensig @igorls
+
+# Core library
+mempalace/ @milla-jovovich @bensig
+
+# CI and workflows
+.github/ @bensig
+
+# Plugins and integrations
+.claude-plugin/ @bensig
+.codex-plugin/ @bensig
+integrations/ @bensig