Enhance mainchain reorg handling with mining pause and robust recovery

src/side_chain.h

@@ -114,6 +114,11 @@ public:
         void check_and_run_deferred_recovery();
         bool is_in_recovery() const { return m_recoveryMode.load(); }
 
+        // Mainchain reorg handling
+        void on_mainchain_reorg(uint64_t split_height, const hash& old_block_hash);
+        bool is_in_reorg_grace_period() const;
+        static constexpr uint64_t REORG_GRACE_PERIOD_SECONDS = 60;
+
 	[[nodiscard]] FORCEINLINE difficulty_type difficulty() const { ReadLock lock(m_curDifficultyLock); return m_curDifficulty; }
 	[[nodiscard]] difficulty_type total_hashes() const;
 	[[nodiscard]] uint64_t block_time() const { return m_targetBlockTime; }
@@ -245,6 +250,10 @@ private:
         std::atomic<uint64_t> m_pendingRecoveryHeight{0};
         bool m_checkpointsNeedValidation{false};
 
+        // Mainchain reorg tracking
+        std::atomic<uint64_t> m_reorgGracePeriodEnd{0};
+        std::atomic<uint64_t> m_lastReorgHeight{0};
+
 	hash m_consensusHash;
 
 	void launch_precalc(const PoolBlock* block);