A reading too big for one packet fails the same way in the Sandbox as on real Reticulum #113

Parent

#27 (M6 General sensors)

Spec: docs/specs/general-sensors.md (added by PR #111; read it there until it merges). Parent: #27.

What to build

The in-memory Mesh refuses a message over the packet limit with the same limit and error as real Reticulum. A Node whose reading won't fit logs an error once per cause, shares nothing that tick, and keeps its publishing loop running; other Nodes carry on. Spec decision 6.

Acceptance criteria

• The in-memory Mesh refuses an oversized message with the same error real Reticulum gives.
• A Node with an oversized reading logs the error once per cause, shares nothing that tick and keeps running; the other Nodes are unaffected.
• A test holds a reading with all eight kinds (flood four, the three new kinds, camera) at realistic values under the 350-byte budget.
• uv run pytest -m mesh_integration is rerun and the result is in the PR; scripts/check.sh node passes.

Blockers are native links.