Initialize CBDD solution and add a .NET-focused gitignore for generated artifacts.

src/CBDD.Core/Transactions/CheckpointMode.cs

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+namespace ZB.MOM.WW.CBDD.Core.Transactions;
+
+/// <summary>
+/// Defines checkpoint modes for WAL (Write-Ahead Log) checkpointing.
+/// Similar to SQLite's checkpoint strategies.
+/// </summary>
+public enum CheckpointMode
+{
+    /// <summary>
+    /// Passive checkpoint: Non-blocking, best-effort transfer from WAL to database.
+    /// Does not wait for readers or writers. May not checkpoint all frames.
+    /// </summary>
+    Passive = 0,
+
+    /// <summary>
+    /// Full checkpoint: Waits for concurrent readers/writers, then checkpoints all
+    /// committed transactions from WAL to database. Blocks until complete.
+    /// </summary>
+    Full = 1,
+
+    /// <summary>
+    /// Truncate checkpoint: Same as Full, but also truncates the WAL file after
+    /// successful checkpoint. Use this to reclaim disk space.
+    /// </summary>
+    Truncate = 2,
+
+    /// <summary>
+    /// Restart checkpoint: Truncates WAL and restarts with a new WAL file.
+    /// Forces a fresh start. Most aggressive mode.
+    /// </summary>
+    Restart = 3
+}