fix(snapshot): import pm_oracle oracle-metrics fields (P1-P5)

[web3blind]

Summary

Follow-up to the P1-P5 oracle-metrics commits on pm (#124): import_pm_oracles() in plugins/snapshot/plugin.cpp skipped the five new display-only pm_oracle_object fields, so a snapshot taken after the upgrade lost them on import.

Why it matters

• Gauges (markets_in_dispute_window, disputes_awaiting_response, disputes_awaiting_decision): were only recoverable when dgpo.pm_oracle_gauges_seeded was absent; if a post-upgrade snapshot carried the seeded flag, they stayed zeroed.
• resolved_late_count + resolution_time_hist: forward-accumulating (no seed) — previously impossible to recover on snapshot import; the histogram and late counter silently reset to 0.

Change

plugins/snapshot/plugin.cpp, inside import_pm_oracles():

if (v.get_object().contains("markets_in_dispute_window"))
    obj.markets_in_dispute_window  = static_cast<uint32_t>(v["markets_in_dispute_window"].as_uint64());
if (v.get_object().contains("disputes_awaiting_response"))
    obj.disputes_awaiting_response = static_cast<uint32_t>(v["disputes_awaiting_response"].as_uint64());
if (v.get_object().contains("disputes_awaiting_decision"))
    obj.disputes_awaiting_decision = static_cast<uint32_t>(v["disputes_awaiting_decision"].as_uint64());
if (v.get_object().contains("resolved_late_count"))
    obj.resolved_late_count  = static_cast<uint32_t>(v["resolved_late_count"].as_uint64());
if (v.get_object().contains("resolution_time_hist"))
    obj.resolution_time_hist = v["resolution_time_hist"].as<fc::array<share_type, 8>>();

Forward-compatible: contains() guards mean pre-upgrade snapshots (fields absent) import cleanly and keep the existing seed-on-first-block behavior; post-upgrade snapshots preserve gauges and the histogram.

fc::array<share_type, 8> serializes through FC_REFLECT as a base64 vector<char> and reads back via the generic from_variant (already used in this plugin for packed_trx etc.).

Verification

• git diff --check clean; single file, 13 insertions, no other changes.
• Display-only fields; no consensus impact (P1-P5 commits explicitly marked them non-gating).
• Full C++ build not run here (no local Boost toolchain); the change mirrors the surrounding contains()-guarded import style exactly.