REBUILD.md: decision g, connections shared by priority

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

REBUILD.md

@@ -326,3 +326,11 @@ f. Random-named releases (no file with a readable name) keep no chunk in
    phase 2 names them (bodies) and fetches their segments again. The full
    history is ~3 TB with them, ~1.2–1.4 TB without (725 M of the 1.25 B
    kept files; LOG.md 2026-10-09). **Accepted** 2026-10-09, not built yet.
+g. The account's NNTP connections shared by priority (`nntp_shares`): the
+   coordinator (headers) before the prober, each between its minimum and
+   maximum, 5 kept for the spotter, the spot inspector, the plain
+   connection and reconnects. A process grows only into connections the
+   others closed, so the account never goes over its limit. Replaces the
+   fixed split (38 + 8), under which the prober stayed at 8 while history
+   was paused and the coordinator's connections idle (LOG.md 2026-10-18
+   (75)). **Accepted** 2026-10-18.