Add MemEventInitRegion broadcast to Samba so that PTW links are discoverable during init

[HenryINUK]

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1 · Background

• Stack Ariel → Samba(MMU) → L1/L2 → Bus → MemController

• self_connected = 0 → Samba’s PTW sends real loads/stores on ptw_to_mem[%d].

• Test-case: any script in opal/tests/ (e.g. XSBench) under SST 15.0.

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2 · Current failures

Stage	Fatal message	Root cause
Init phase	MMU unreachable	Samba never advertises a Region for ptw_to_mem.
Run phase (after fixing above)	l1cache_0 maximum cache timeout	do not know reason yet... .

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3 · Fix #1 – make PTW visible (works)

// Samba::init()
if (phase == 0 && !self_connected) {
    MemHierarchy::MemRegion all; all.setDefault();      // 0-0xFFFF…
    auto* reg = new MemHierarchy::MemEventInitRegion(
                    getName(), all,
                    MemHierarchy::MemEventInitRegion::ReachableGroup::Source);
    ptw_to_mem[i]->sendUntimedData(reg);
}

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So the second error remains, please fix it.
Thanks.