Slice 2: telemetry, vitals, chat, spawn/portal, rare, kills and combat stats

The frames the backend reads most, each pinned by a golden test written from
the original's source (field order, JSON types, string-formatted numbers,
mem_mb in bytes, the PascalCase aggregates Newtonsoft emits for combat_stats).
Coordinates repeat the original's float arithmetic from the landblock-local
float, so ew/ns carry the same float-widened values as before. Telemetry goes
out on connect and every 5 s, vitals every 5 s, combat stats every 10 s when
dirty. The rare meta-state switch is not carried over (owner decision); the
allegiance rare announcement and the !report reply are. Kill patterns and
combat patterns are the original's, unchanged.

Also fixes the tick scheduler re-arming repeating jobs from now instead of
from their due time, which made every cadence drift a frame late per period.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

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