feat: law-source-eurlex 0.1.0 (source.eu-recht)

Fetch one EU legal act from EUR-Lex by CELEX number and return its
FORMEX-4 XML content-addressed (SHA-256), so a flow's audit trail
pins the exact Gesetzesstand it processed.

- CELLAR content negotiation (application/xml;type=fmx4) on
  publications.europa.eu; 303 multiple-choice item selection
- host-pinned redirect handling (max 3 hops), 64 MB body cap
- consolidated CELEX (0...-YYYYMMDD) yields consolidation_date
- net permission pinned to publications.europa.eu; no auth
- 10 unit tests (no network), wasm32-wasip2 build green

Signed-off-by: flemming-it <sf@flemming.it>

NOTICE

@@ -0,0 +1,28 @@
+law-source-eurlex
+Copyright 2026 Flemming.AI
+
+This product includes software developed by Dr. Stefan Flemming
+and contributors (https://flemming.ai/).
+
+------------------------------------------------------------------
+Third-party acknowledgments
+
+XML parsing uses the `quick-xml` crate
+(https://github.com/tafia/quick-xml), MIT licensed.
+
+SHA-256 hashing uses the `sha2` crate
+(https://github.com/RustCrypto/hashes), Apache-2.0 / MIT licensed.
+
+Module SDK glue is provided by `chain-module-sdk`
+(https://git.flemming.ai/fai/chain-module-sdk-rust), Apache-2.0.
+
+------------------------------------------------------------------
+Methodological lineage
+
+The output schema is aligned with Akoma Ntoso 1.0 (OASIS
+LegalDocML), the XML format the European Parliament has used
+since 2016 for legislative texts.
+
+ELI synthesis in v0.1.0 is a deterministic fallback because
+Germany lacks an upstream Bund-level ELI registrar. Replace once
+BMJ publishes ELI URIs upstream.