Merge DATUM ngit proposal with preserved catalog entries

Reviewed ngit proposal 15ff5fb9 (pr/datum), head febdda968e. Preserve all existing catalog entries and normalize the new manifest memory limit to supported 512m syntax.

Validation: three configuration preservation tests and strict release catalog drift pass. Live miner shares, payout configuration and reboot acceptance remain separate.

neode-ui/src/views/appSession/generatedAppSessionConfig.ts

@@ -10,6 +10,7 @@ export const GENERATED_APP_PORTS: Record<string, number> = {
   "botfights": 9100,
   "btcpay-server": 23000,
   "cuprate-ui": 18091,
+  "datum": 7152,
   "electrs-ui": 50002,
   "electrumx": 50002,
   "fedimint": 8175,
@@ -59,6 +60,7 @@ export const GENERATED_APP_TITLES: Record<string, string> = {
   "core-lightning": "Core Lightning (CLN)",
   "cuprate": "Cuprate",
   "cuprate-ui": "Cuprate UI",
+  "datum": "DATUM",
   "electrs-ui": "Electrs UI",
   "electrumx": "ElectrumX",
   "fedimint": "Fedimint Guardian",