feat(unicode,datastruct): port Unicode tables and data structures

ghostty-unicode: Ghostty computes codepoint properties with the uucode
Zig package (v0.2.0, Unicode 17.0.0). There is no Rust equivalent, so
a trimmed UCD set is vendored in ucd/ and build.rs re-implements
uucode's derivations: cell width rules incl. Ghostty's overrides for
emoji modifiers and Prepend, grapheme break classes with the
compile-time grapheme_break state table, the is_symbol set, and emoji
presentation. Lookups are three array indexes per codepoint. Validated
against the official GraphemeBreakTest.txt.

ghostty-datastruct: split_tree (used for GTK splits; f16 ratios so
rounding and debug diagrams match Zig), circ_buf, lru, cache_table,
blocking_queue, segmented_pool, message_data, comparison,
array_list_collection. intrusive_linked_list is not needed (lru is
index based). lru now reports the evicted (old) key, Zig reported the
new key, which appears to be a bug.

Not yet covered: case_folding_full (needed by input bindings).

Test Plan:
- cargo test -p ghostty-unicode (16) -p ghostty-datastruct (88)
- cargo clippy for both crates with -D warnings

crates/ghostty-unicode/build.rs

@@ -0,0 +1,57 @@
+//! Generates the Unicode lookup tables (Ghostty's `props_uucode.zig` /
+//! `symbols_uucode.zig` generator `main`s) from the vendored UCD files in
+//! `ucd/`.
+#![allow(dead_code)]
+#![allow(
+    clippy::unwrap_used,
+    clippy::single_match_else,
+    clippy::checked_conversions,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::expect_used
+)]
+
+#[path = "src/lut.rs"]
+mod lut;
+#[path = "src/props.rs"]
+mod props;
+#[path = "build_support/ucd.rs"]
+mod ucd;
+
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+fn main() {
+    let manifest = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let out = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    let ucd_dir = manifest.join("ucd");
+
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=build_support/ucd.rs");
+    println!("cargo:rerun-if-changed=src/lut.rs");
+    println!("cargo:rerun-if-changed=src/props.rs");
+    println!("cargo:rerun-if-changed=ucd");
+
+    let ucd = ucd::Ucd::load(&ucd_dir);
+
+    let props = lut::generate(|cp| ucd.get(cp)).expect("generate props tables");
+    fs::write(
+        out.join("props_tables.rs"),
+        props.write_rust("Properties", props::Properties::format_rust),
+    )
+    .unwrap();
+
+    let symbols = lut::generate(|cp| ucd.is_symbol(cp)).expect("generate symbols tables");
+    fs::write(
+        out.join("symbols_tables.rs"),
+        symbols.write_rust("bool", ToString::to_string),
+    )
+    .unwrap();
+
+    let emoji = lut::generate(|cp| ucd.is_emoji_presentation(cp)).expect("generate emoji tables");
+    fs::write(
+        out.join("emoji_tables.rs"),
+        emoji.write_rust("bool", ToString::to_string),
+    )
+    .unwrap();
+}