fix(security): remediate unassigned CodeQL findings

- harden URL/request handling for composio and whatsapp integrations
- reduce cleartext logging exposure across providers/tools/gateway
- hash and constant-time compare gateway webhook secrets
- expand nested secret encryption coverage in config
- align feature aliases and add regression tests for security paths
- fix bubblewrap all-features test invocation surfaced during deep validation

Cargo.toml

@@ -63,9 +63,6 @@ rand = "0.8"
 # Fast mutexes that don't poison on panic
 parking_lot = "0.12"
 
-# Landlock (Linux sandbox) - optional dependency
-landlock = { version = "0.4", optional = true }
-
 # Async traits
 async-trait = "0.1"
 
@@ -120,14 +117,24 @@ probe-rs = { version = "0.30", optional = true }
 # PDF extraction for datasheet RAG (optional, enable with --features rag-pdf)
 pdf-extract = { version = "0.10", optional = true }
 
-# Raspberry Pi GPIO (Linux/RPi only) — target-specific to avoid compile failure on macOS
+# Raspberry Pi GPIO / Landlock (Linux only) — target-specific to avoid compile failure on macOS
 [target.'cfg(target_os = "linux")'.dependencies]
 rppal = { version = "0.14", optional = true }
+landlock = { version = "0.4", optional = true }
 
 [features]
 default = ["hardware"]
 hardware = ["nusb", "tokio-serial"]
 peripheral-rpi = ["rppal"]
+# Browser backend feature alias used by cfg(feature = "browser-native")
+browser-native = ["dep:fantoccini"]
+# Backward-compatible alias for older invocations
+fantoccini = ["browser-native"]
+# Sandbox feature aliases used by cfg(feature = "sandbox-*")
+sandbox-landlock = ["dep:landlock"]
+sandbox-bubblewrap = []
+# Backward-compatible alias for older invocations
+landlock = ["sandbox-landlock"]
 # probe = probe-rs for Nucleo memory read (adds ~50 deps; optional)
 probe = ["dep:probe-rs"]
 # rag-pdf = PDF ingestion for datasheet RAG