fix: resolve all post-merge compile errors

- Fix unresolved imports (auto_compaction, AutoCompactionEvent)
- Add Thinking/RedactedThinking match arms
- Fix workspace.dependencies serde_json
- Fix enum exhaustiveness in OutputContentBlock matches
- cargo check --workspace passes

rust/crates/commands/Cargo.toml

@@ -11,4 +11,4 @@ workspace = true
 [dependencies]
 plugins = { path = "../plugins" }
 runtime = { path = "../runtime" }
-serde_json = "1"
+serde_json.workspace = true