Review fixes: telemetry session id per login; Framework number text

F1: the telemetry session id is new at every login. The original made one per
load of its assembly and its loader reloaded it at every login; the backend
counts new kills per (session id, character), so reusing one id across a
relog under-counted kills until the reset counter passed the old total.

F5/F6: .NET Framework never wrote a negative zero, and its fixed-point
formats (F7, F2, F0) rounded at fifteen significant digits, half away from
zero. Spawn and portal coordinates, kills_per_hour and the !report line now
format that way; the round-trip converter maps -0 to 0.

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

tests/OpenAC.MosswartMassacre.Tests/Streams/StreamGoldenTests.cs

@@ -142,7 +142,7 @@ public sealed class StreamGoldenTests
         Assert.Equal(expectedOrder, frame.Properties().Select(p => p.Name));
 
         string head = "{\"type\":\"telemetry\",\"character_name\":\"Mossy\",\"char_tag\":\"tank\",\"session_id\":\""
-            + MmContext.ProcessSessionId + "\",\"timestamp\":\"2026-09-25T10:00:15.1230000Z\","
+            + harness.Context.TelemetrySessionId + "\",\"timestamp\":\"2026-09-25T10:00:15.1230000Z\","
             + "\"ew\":" + D(33.65f) + ",\"ns\":" + D(42.55f) + ",\"z\":42.5,\"kills\":0,"
             + "\"kills_per_hour\":\"0\",\"onlinetime\":\"00.01:30:00\",\"deaths\":\"0\",\"total_deaths\":\"7\","
             + "\"prismatic_taper_count\":\"1234\",\"vt_state\":\"Combat\",\"mem_mb\":";