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>

MODULE.md

@@ -0,0 +1,46 @@
+# source.eu-recht
+
+<!-- chain:io-card:start -->
+<!-- Generated by `chain doc` from module.yaml — do not edit by hand. -->
+![law-source-eurlex inputs and outputs](law-source-eurlex.io.svg)
+<!-- chain:io-card:end -->
+
+Fetch EU legal acts from EUR-Lex by CELEX number
+
+## What it does
+
+Resolves a CELEX identifier (e.g. `32016R0679` for the GDPR, or the
+consolidated form `02016R0679-20160504`) against the public EUR-Lex
+CELLAR endpoint and returns the act's FORMEX-4 XML plus a
+metadata record. The fetched bytes are content-addressed (SHA-256),
+so the flow's audit trail pins the exact Gesetzesstand that was
+processed — a later re-fetch of "the same" CELEX that renders
+differently upstream becomes visible instead of silent.
+
+Public EUR-Lex data only; network permission is pinned to
+`publications.europa.eu` (CELLAR, the EU Publications Office store
+behind EUR-Lex).
+
+## How to use
+
+```yaml
+steps:
+  - id: fetch
+    use: source.eu-recht@^0
+    with:
+      celex: "32016R0679"
+      language: "DE"          # optional, default DE
+  - id: normalize
+    use: text.akoma-normalize@^0    # 0.2+ understands FORMEX-4
+    with:
+      content: "{{ fetch.formex }}"
+      mime: "application/x-formex+xml"
+```
+
+Outputs: `formex` (bytes, `application/xml`) and `meta` (JSON with
+`celex`, `language`, `url`, `source_sha256`, `byte_len`, and
+`consolidation_date` for consolidated CELEX numbers).
+
+## License
+
+Apache-2.0 — a Ch∆In platform module (Flemming.AI).