Preserve local project context across compaction and todo updates

This change makes compaction summaries durable under .claude/memory,
feeds those saved memory files back into prompt context, updates /memory
to report both instruction and project-memory files, and moves TodoWrite
persistence to a human-readable .claude/todos.md file.

Constraint: Reuse existing compaction, prompt loading, and slash-command plumbing rather than add a new subsystem
Constraint: Keep persisted project state under Claude-local .claude/ paths
Rejected: Introduce a dedicated memory service module | larger diff with no clear user benefit for this task
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Project memory files are loaded as prompt context, so future format changes must preserve concise readable content
Tested: cargo fmt --all --manifest-path rust/Cargo.toml
Tested: cargo clippy --manifest-path rust/Cargo.toml --all-targets --all-features -- -D warnings
Tested: cargo test --manifest-path rust/Cargo.toml --all
Not-tested: Long-term retention/cleanup policy for .claude/memory growth

rust/crates/runtime/src/conversation.rs

@@ -408,13 +408,14 @@ mod tests {
                 .sum::<i32>();
             Ok(total.to_string())
         });
-        let permission_policy = PermissionPolicy::new(PermissionMode::Prompt);
+        let permission_policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite);
         let system_prompt = SystemPromptBuilder::new()
             .with_project_context(ProjectContext {
                 cwd: PathBuf::from("/tmp/project"),
                 current_date: "2026-03-31".to_string(),
                 git_status: None,
                 instruction_files: Vec::new(),
+                memory_files: Vec::new(),
             })
             .with_os("linux", "6.8")
             .build();
@@ -487,7 +488,7 @@ mod tests {
             Session::new(),
             SingleCallApiClient,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Prompt),
+            PermissionPolicy::new(PermissionMode::WorkspaceWrite),
             vec!["system".to_string()],
         );
 
@@ -536,7 +537,7 @@ mod tests {
             session,
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
 
@@ -563,7 +564,7 @@ mod tests {
             Session::new(),
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
         runtime.run_turn("a", None).expect("turn a");