Add external agent memory migration (#33444)

## What changed

- Add a feature-gated `MEMORY` migration item to the app-server protocol and TUI.
- Discover project memory Markdown files, preserve their project scope, and copy selected projects into the Codex memory extension workspace.
- Detect changed, renamed, and removed source projects, report per-project import failures, and enqueue memory consolidation after workspace changes.

## Testing

- Cover memory discovery, selection, synchronization, scope validation, feature gating, protocol results, and TUI rendering.

GitOrigin-RevId: 9b17b2e9a639a064dba8aaffbec6345ae419018e

codex-rs/app-server-protocol/src/protocol/v2/config.rs

@@ -575,6 +575,9 @@ pub enum ExternalAgentConfigMigrationItemType {
     #[serde(rename = "COMMANDS")]
     #[ts(rename = "COMMANDS")]
     Commands,
+    #[serde(rename = "MEMORY")]
+    #[ts(rename = "MEMORY")]
+    Memory,
     #[serde(rename = "SESSIONS")]
     #[ts(rename = "SESSIONS")]
     Sessions,
@@ -654,6 +657,8 @@ pub struct MigrationDetails {
     pub subagents: Vec<SubagentMigration>,
     #[serde(default)]
     pub commands: Vec<CommandMigration>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub memory: Vec<String>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]