refactor(config): parse config values from raw bytes like Zig

Zig parses config values (cli/args.zig, Config.zig field parsers,
config/string.zig) from raw byte slices, and each field type decides
whether it requires UTF-8 (InvalidValue otherwise) or stores bytes. The
port escape-encoded raw bytes into Strings at the line reader and let
fields parse the escaped text, so fields could observe encoding
artifacts; successive audits kept finding such leaks (RV5-RV8).

Field parsers now receive the original bytes: text fields validate UTF-8
where Zig does, byte/path fields store bytes (EncodedOs/OsString). This
resolves all 9 RV8 findings (docs/rewrite/notes/review-rv8-codex.md),
each with a regression test: Windows path conversion fails with
BadPathName instead of substituting U+FFFD; Windows process launch uses
strict UTF-8 like Zig's Command; the WTF-8 decoder accepts paired-
surrogate encodings like Zig; literal U+FDD0 Unicode key triggers;
selection-word-chars and clipboard-codepoint-map reject invalid UTF-8;
font style / codepoint-map family names use original bytes; C title
actions forward bytes; D-Bus new-window/Flatpak conversions match Zig.
Design, sweep and validation: docs/rewrite/notes/final-bytes-refactor.md.

Also moves the bundled iTerm2-Color-Schemes license out of
resources/themes/ so +list-themes no longer lists it as a theme
(output is now byte-identical to Ghostty 1.3.1).

Done by Codex (gpt-6-astra), reviewed and verified by the orchestrator.

Test Plan:
- cargo test --workspace --no-fail-fast (3428 passed, exit 0)
- just check-macos (both), just check-windows, just check-wasm
- +show-config --default --docs, +list-keybinds, +list-actions --docs,
  +list-themes --plain compared with /usr/bin/ghostty

crates/ghostty-font/src/shaper/feature.rs

@@ -344,7 +344,11 @@ impl FeatureList {
     /// Append features to this list from a string with a comma separated list.
     /// See `Feature::from_reader` for more docs.
     pub fn append_from_string(&mut self, s: &str) {
-        let mut reader = Reader::new(s.as_bytes());
+        self.append_from_bytes(s.as_bytes());
+    }
+
+    pub fn append_from_bytes(&mut self, s: &[u8]) {
+        let mut reader = Reader::new(s);
         while !reader.at_end() {
             let i = reader.pos;
             if let Some(feature) = Feature::from_reader(&mut reader) {
@@ -352,7 +356,7 @@ impl FeatureList {
             } else {
                 log::warn!(
                     "failed to parse font feature setting: \"{}\"",
-                    String::from_utf8_lossy(&s.as_bytes()[i..reader.pos])
+                    String::from_utf8_lossy(&s[i..reader.pos])
                 );
             }
         }