FEAT: Add the 51Did (FodId) reader module (pipeline.did)

[oleksandrlazarenko-pi]

Summary

Adds pipeline.did, a strongly typed Java reader for the 51Did (51Degrees
Identifier) value returned by the 51Degrees Cloud service. Mirrors the .NET
FiftyOne.Did package. Also adds an offline developer example.

What it does

• FodId parses a 51Did from its base64 OWID form and exposes the payload
  fields — getFlags(), getLicenseId() (unsigned little-endian as long),
  getHash() (the stable value, defensive copy), and getType() — plus the
  OWID-level fields via the wrapped envelope.
• Implements the live Type model (flag bits 6-7: Probabilistic / Random /
  HashedEmail / Reserved) with per-type value length (16 or 32 bytes).
• Composition over OWID (owid-java's Owid is final). Construction does
  not verify the signature; verify(publicPem) is an explicit, separate
  call.

OWID dependency

Builds on owid-java (com.swancommunity.owid), consumed from the
51Degrees/owid-java fork as a git submodule (owid-java/) whose source is
compiled into the module (mirroring how pipeline-dotnet compiles owid-dotnet
in). The submodule is pinned to the fork's feature/java8-baseline branch,
which lowers the OWID build to Java 8 to match pipeline-java
(owid-java targets Java 21 upstream).

The submodule will be repointed to owid-java main once the fork PR
(51Degrees/owid-java#2) lands;
the upstream change is SWAN-community/owid-java#1.

Build & enforcement

• New module pipeline.did registered in the aggregator pom.xml; Java 8;
  EUPL-1.2 headers.
• The HTTP-only Endpoints OWID class is excluded from compilation (not needed
  for offline parse + verify).
• animal-sniffer is wired to the java18 signature so the build fails on
  any Java 9+ API — this is what guarantees the Java 8 floor (the parent's
  -source/-target 1.8 alone does not catch newer JDK APIs).

Tests & example

• FodIdTests (JUnit 4): the full ported .NET suite including the Type-model
  cases plus the runbook gap tests — 31 tests, all passing. Verify cases run
  offline (owid-java has offline verify).
• pipeline.developer-examples.fodid — a self-contained offline example
  (build, parse, compare two 51Dids) with an ExampleTests smoke test.
• Verified locally: mvn -pl pipeline.did test green, and the full reactor
  mvn -DskipTests install builds all modules including the two new ones.

Notes for reviewers

• FodId uses static factories (fromBase64 / fromByteArray / fromOwid)
  because owid-java's parse throws the checked OwidException.
• The from-OWID test asserts payload/signature by value (assertArrayEquals),
  not identity, because owid-java getters return clones.

[Jamesr51d]

This Java module copies the OWID source files into itself when it builds rather than just depending on it.
The final pipeline.did.jar will contain:

51Degrees code, licensed EUPL-1.2
OWID code (com.swancommunity.owid.* classes), licensed Apache-2.0

For the Apache-2.0 licence, every copy must come with a copy of the Apache licence text and a credit saying what it is and where it came from. Right now the jar contains the OWID code but not the licence text or credit, so anyone who downloads the jar from maven is receiving Apache-licensed code without the paperwork that Apache-2.0 requires to travel with it.