feat(middleware): add DataMaskingMiddleware — sensitive entity protection (Chunk 3)

Priority 90 — runs before Compaction@100 and Memory@150.
Detects and replaces company names, money amounts, phone numbers,
emails, and ID card numbers with deterministic tokens (__ENTITY_N__).
External callers can restore originals via DataMasker::unmask().

crates/zclaw-runtime/Cargo.toml

@@ -24,6 +24,7 @@ uuid = { workspace = true }
 chrono = { workspace = true }
 tracing = { workspace = true }
 async-trait = { workspace = true }
+regex = { workspace = true }
 
 # HTTP client
 reqwest = { workspace = true }