[feat](trx-config): report unknown configuration keys

Every config struct is #[serde(default)], so a misspelled key was dropped in
silence and the setting kept its default.  Writing `prot = 9999` under
[listen] started the server on 4530 without a word.

Collect the ignored key paths with serde_ignored and pair each with the
closest known key at the same level:

    WARN unknown config key 'listen.prot' (did you mean 'listen.port'?)

Warnings by default, so a config written for a newer version still runs on an
older binary; --strict-config makes them fatal for CI.  Logging now starts
before validation so these warnings are actually visible.

trx-configurator --check drops its hand-maintained key lists and re-implemented
range checks in favour of the real loader and validators, so it no longer
passes configs the binaries reject.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SyX26FCpMQxiBoC7r5K1A7
Signed-off-by: Stan Grams <sjg@haxx.space>

Cargo.lock

@@ -2412,6 +2412,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_ignored"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "115dffd5f3853e06e746965a20dcbae6ee747ae30b543d91b0e089668bb07798"
+dependencies = [
+ "serde",
+ "serde_core",
+]
+
 [[package]]
 name = "serde_json"
 version = "1.0.149"
@@ -3127,6 +3137,7 @@ version = "0.1.0"
 dependencies = [
  "dirs",
  "serde",
+ "serde_ignored",
  "thiserror 2.0.18",
  "toml",
  "tracing",
@@ -3143,6 +3154,7 @@ dependencies = [
  "dialoguer",
  "tempfile",
  "tokio-serial",
+ "toml",
  "toml_edit 0.22.27",
  "trx-config",
 ]