Add configurable memory versions with isolated storage (#43797)

## What changed

- Add `memories.version` with `v1` as the default and `v2` as an opt-in selection.
- Route memory generation, summaries, and retrieval tools through the selected version. Store `v2` artifacts in `memories_v2` and lazily create a separate SQLite database, keeping jobs and outputs isolated while sharing the thread catalog.
- Preserve the initial memory version across extension config updates so summaries and retrieval tools use the same namespace.
- Clear both versions on memory reset and remove thread memory from both stores on thread deletion. Recognize both artifact roots in shell usage telemetry.

## Testing

Add regression coverage for version defaults and validation, independent job claims and outputs, deletion and reset across versions, and shell usage classification for both memory roots.

GitOrigin-RevId: aa799bf87ab6ec10c8f5668213931e57547d080b

codex-rs/protocol/src/lib.rs

@@ -32,6 +32,8 @@ pub mod mcp;
 pub mod mcp_approval_meta;
 pub mod mcp_policy;
 pub mod memory_citation;
+mod memory_version;
+pub use memory_version::MemoryVersion;
 pub mod models;
 pub mod network_policy;
 pub mod num_format;

codex-rs/protocol/src/memory_version.rs

@@ -0,0 +1,23 @@
+//! Selects a coherent memory pipeline and its generated-artifact namespace.
+
+use schemars::JsonSchema;
+use serde::Deserialize;
+use serde::Serialize;
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum MemoryVersion {
+    #[default]
+    V1,
+    V2,
+}
+
+impl MemoryVersion {
+    /// Sibling roots keep v1 cleanup and rollback independent of v2 artifacts.
+    pub fn directory_name(self) -> &'static str {
+        match self {
+            Self::V1 => "memories",
+            Self::V2 => "memories_v2",
+        }
+    }
+}