Javadoc cites nonexistent spec subsections (§5.1, §4.2, §4.1)

[nficano]

Category: docs Severity: minor
Location: arcp-core/src/main/java/dev/arcp/core/wire/ArcpMapper.java:14

What

ARCP v1.1 has no §5.1, §4.2, or §4.1 — the relevant rules live in §5 (Wire Format) and §4 (Transport), which have no subsections. The wrong citations appear in:

• arcp-core/.../wire/ArcpMapper.java:14 and arcp-core/.../wire/Envelope.java:18-19 (§5.1)
• arcp-core/.../transport/StdioTransport.java:25 (§4.2)
• arcp-runtime-jetty/.../jetty/WebSocketJsonTransport.java:21 (§4.1)
• arcp-tck/.../tck/ConformanceSuite.java:58 (test label "§5.1 envelope round-trip via session.welcome")

Evidence

   *   <li>{@code FAIL_ON_UNKNOWN_PROPERTIES=false}: §5.1 mandates ignoring unknown fields.

Proposed fix

Replace §5.1 with §5, and §4.1/§4.2 with §4, in the cited Javadoc and the TCK test label.

Acceptance criteria

• All in-code spec citations reference sections that exist in draft-arcp-1.1.md.