Feat/genesis fix: deterministic genesis tie-break and topic reset

[St4NNi]

This is a genesis collision issue where two genesis blocks are created on different nodes preventing them from ever merging.

Related: arunaengine/aruna#309, arunaengine/aruna#310

Summary

• Add deterministic genesis collision handling so nodes pick the smaller valid genesis op id and converge on the same topic chain.
• Add storage reset primitives for memory and fjall, including atomic reset-and-admit for adopting the winning genesis.
• Surface evicted losing-chain payloads through TopicEviction and optional iroh eviction sinks so embedders can re-emit them on the winning chain.
• Purge losing pending ops and clear stale per-topic sync state so ack clocks can converge after reset.
• Add coverage for tie-break symmetry, reset completeness, pending-op edge cases, fjall reset behavior, and iroh eviction forwarding.

[das-Abroxas]

Nice changes that strengthen the sync and collision-handling path so the system behaves more predictably and safely under competing topic histories. lgtm.