feat: initialize bangwen recruitment aggregation and search engine

- Rust core engine with HTTP ingestion gateway, hybrid search, and white-box resume matching
- Python edge collectors supporting declarative TOML and specialized adapters
- PostgreSQL schema migrations with pgvector embedding support
- Hardened security controls: strict CSP, terminal sanitization, and input boundary validation
- Multi-service container orchestration with dedicated non-root execution

collectors/README.md

@@ -0,0 +1,25 @@
+# Bangwen Collectors
+
+Lightweight declarative and custom python collectors for the Bangwen public job posting aggregation system.
+
+## Structure
+
+- `sources/`: Declarative TOML configuration for crawling target sites.
+- `adapters/`: Custom Python scrapers for complex or stateful collection logic.
+- `common/`: Core fetcher, security validators, and ingestion protocol models.
+- `runner.py`: Periodic crawler runner and domain-concurrency scheduler.
+
+## Running
+
+```bash
+uv run python runner.py --list
+uv run python runner.py --once
+```
+
+## Testing
+
+Unit tests for collectors, SSRF guards, and content sanitizers are excluded from production Docker images and can be run directly on the host:
+
+```bash
+cd collectors && uv run python tests/test_content_and_security.py
+```