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/src/props.rs

@@ -0,0 +1,100 @@
+//! Property set per codepoint that Ghostty cares about.
+//!
+//! Adding to this lets you find new properties but also potentially makes
+//! our lookup tables less efficient.
+//!
+//! NOTE: this file is also `#[path]`-included by `build.rs`, so it must not
+//! depend on anything else in the crate.
+
+/// Grapheme break property with the control/CR/LF classes removed
+/// (`uucode.x.types.GraphemeBreakNoControl`). The discriminant order matches
+/// uucode and is used to index the precomputed break table.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
+#[repr(u8)]
+pub enum GraphemeBreakNoControl {
+    #[default]
+    Other = 0,
+    Prepend,
+    RegionalIndicator,
+    SpacingMark,
+    L,
+    V,
+    T,
+    Lv,
+    Lvt,
+    Zwj,
+    Zwnj,
+    ExtendedPictographic,
+    EmojiModifierBase,
+    EmojiModifier,
+    // extend, ==
+    //   zwnj +
+    //   indic_conjunct_break_extend +
+    //   indic_conjunct_break_linker
+    IndicConjunctBreakExtend,
+    IndicConjunctBreakLinker,
+    IndicConjunctBreakConsonant,
+}
+
+impl GraphemeBreakNoControl {
+    /// Number of variants.
+    pub const COUNT: usize = 17;
+
+    /// Variant name in Rust syntax (used by the table generator).
+    #[must_use]
+    pub const fn rust_name(self) -> &'static str {
+        match self {
+            Self::Other => "Other",
+            Self::Prepend => "Prepend",
+            Self::RegionalIndicator => "RegionalIndicator",
+            Self::SpacingMark => "SpacingMark",
+            Self::L => "L",
+            Self::V => "V",
+            Self::T => "T",
+            Self::Lv => "Lv",
+            Self::Lvt => "Lvt",
+            Self::Zwj => "Zwj",
+            Self::Zwnj => "Zwnj",
+            Self::ExtendedPictographic => "ExtendedPictographic",
+            Self::EmojiModifierBase => "EmojiModifierBase",
+            Self::EmojiModifier => "EmojiModifier",
+            Self::IndicConjunctBreakExtend => "IndicConjunctBreakExtend",
+            Self::IndicConjunctBreakLinker => "IndicConjunctBreakLinker",
+            Self::IndicConjunctBreakConsonant => "IndicConjunctBreakConsonant",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
+pub struct Properties {
+    /// Codepoint width. We clamp to [0, 2] since Ghostty handles control
+    /// characters and we max out at 2 for wide characters (i.e. 3-em dash
+    /// becomes a 2-em dash). (`u2` in Zig.)
+    pub width: u8,
+
+    /// Whether the code point does not contribute to the width of a grapheme
+    /// cluster (not used for single code point cells).
+    pub width_zero_in_grapheme: bool,
+
+    /// Grapheme break property.
+    pub grapheme_break: GraphemeBreakNoControl,
+
+    /// Emoji VS compatibility
+    pub emoji_vs_base: bool,
+}
+
+impl Properties {
+    /// Rust source expression for this value (the Zig `format`), used by the
+    /// build script when writing the generated tables.
+    #[must_use]
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn format_rust(&self) -> String {
+        format!(
+            "Properties {{ width: {}, width_zero_in_grapheme: {}, grapheme_break: GraphemeBreakNoControl::{}, emoji_vs_base: {} }}",
+            self.width,
+            self.width_zero_in_grapheme,
+            self.grapheme_break.rust_name(),
+            self.emoji_vs_base,
+        )
+    }
+}