remove unused rustls-pemfile dependency

Dead code — certs are generated at startup, not loaded from PEM files.
Removes RUSTSEC-2025-0134 warning. Audit now passes clean.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -944,7 +944,6 @@ dependencies = [
  "rcgen",
  "reqwest",
  "rustls",
- "rustls-pemfile",
  "serde",
  "serde_json",
  "time",
@@ -1275,15 +1274,6 @@ dependencies = [
  "zeroize",
 ]
 
-[[package]]
-name = "rustls-pemfile"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dce314e5fee3f39953d46bb63bb8a46d40c2f8fb7cc5a3b6cab2bde9721d6e50"
-dependencies = [
- "rustls-pki-types",
-]
-
 [[package]]
 name = "rustls-pki-types"
 version = "1.14.0"