Add base64 input for eval command (#340)

* Add base64 input for eval command

Adds -b/--base64 flag to decode script from base64, avoiding shell escaping issues for AI agents.

* Document base64 eval in SKILL.md

cli/Cargo.lock

@@ -6,6 +6,7 @@ version = 4
 name = "agent-browser"
 version = "0.8.7"
 dependencies = [
+ "base64",
  "dirs",
  "libc",
  "serde",
@@ -13,6 +14,12 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "base64"
+version = "0.22.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
+
 [[package]]
 name = "bitflags"
 version = "2.10.0"