docs: clarify primitive schema byte order

[singhvishalkr]

Motivation

Primitive schema docs list the supported types, but they do not state how fixed-width numeric values are ordered on the wire. That leaves client implementers to infer byte order when producers and consumers are not using the same client library.

Modifications

• Clarify that Java primitive schemas encode fixed-width numeric values in big-endian byte order.
• Note that INT8 is a single byte, FLOAT and DOUBLE use IEEE 754 bit patterns, and BYTES payloads keep application-defined ordering.
• Apply the same clarification to the current docs and supported versioned docs (4.0.x and 4.2.x).

Verifying this change

• corepack yarn install --immutable
• git diff --check
• corepack yarn typecheck fails on existing non-doc TypeScript issues in matomoClientModule.ts and src/theme/Blog* files.
• $env:NODE_OPTIONS='--max_old_space_size=16000'; corepack yarn docusaurus build passes; it emits existing site-wide broken-link and SSG warnings outside the changed schema docs.

Contribution Checklist

• I read the contribution guide
• I updated the versioned docs

Fixes #1142