Load maps from TOML files with XPM-style palette

Introduces a map file format: TOML with a [palette] mapping characters
to (Glyph, Element) definitions and a [grid] multi-line string. Board
now owns the player position, objects, and portals. map_file::load()
deserializes a file and converts it to a Board via From<MapFile>.

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

Cargo.lock

@@ -2369,7 +2369,7 @@ version = "3.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e67ba7e9b2b56446f1d419b1d807906278ffa1a658a8a5d8a39dcb1f5a78614f"
 dependencies = [
- "toml_edit",
+ "toml_edit 0.25.11+spec-1.1.0",
 ]
 
 [[package]]
@@ -2650,6 +2650,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_spanned"
+version = "0.6.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf41e0cfaf7226dca15e8197172c295a782857fcb97fad1808a166870dee75a3"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -2967,6 +2976,27 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "toml"
+version = "0.8.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc1beb996b9d83529a9e75c17a1686767d148d70663143c7854d8b4a09ced362"
+dependencies = [
+ "serde",
+ "serde_spanned",
+ "toml_datetime 0.6.11",
+ "toml_edit 0.22.27",
+]
+
+[[package]]
+name = "toml_datetime"
+version = "0.6.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22cddaf88f4fbc13c51aebbf5f8eceb5c7c5a9da2ac40a13519eb5b0a0e8f11c"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "toml_datetime"
 version = "1.1.1+spec-1.1.0"
@@ -2976,6 +3006,20 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "toml_edit"
+version = "0.22.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41fe8c660ae4257887cf66394862d21dbca4a6ddd26f04a3560410406a2f819a"
+dependencies = [
+ "indexmap",
+ "serde",
+ "serde_spanned",
+ "toml_datetime 0.6.11",
+ "toml_write",
+ "winnow 0.7.15",
+]
+
 [[package]]
 name = "toml_edit"
 version = "0.25.11+spec-1.1.0"
@@ -2983,9 +3027,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b59c4d22ed448339746c59b905d24568fcbb3ab65a500494f7b8c3e97739f2b"
 dependencies = [
  "indexmap",
- "toml_datetime",
+ "toml_datetime 1.1.1+spec-1.1.0",
  "toml_parser",
- "winnow",
+ "winnow 1.0.3",
 ]
 
 [[package]]
@@ -2994,9 +3038,15 @@ version = "1.1.2+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2abe9b86193656635d2411dc43050282ca48aa31c2451210f4202550afb7526"
 dependencies = [
- "winnow",
+ "winnow 1.0.3",
 ]
 
+[[package]]
+name = "toml_write"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d99f8c9a7727884afe522e9bd5edbfc91a3312b36a77b5fb8926e4c31a41801"
+
 [[package]]
 name = "tracing"
 version = "0.1.44"
@@ -3120,6 +3170,8 @@ version = "0.1.0"
 dependencies = [
  "eframe",
  "rhai",
+ "serde",
+ "toml",
 ]
 
 [[package]]
@@ -3980,6 +4032,15 @@ dependencies = [
  "xkbcommon-dl",
 ]
 
+[[package]]
+name = "winnow"
+version = "0.7.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df79d97927682d2fd8adb29682d1140b343be4ac0f08fd68b7765d9c059d3945"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "winnow"
 version = "1.0.3"
@@ -4204,7 +4265,7 @@ dependencies = [
  "uds_windows",
  "uuid",
  "windows-sys 0.61.2",
- "winnow",
+ "winnow 1.0.3",
  "zbus_macros",
  "zbus_names",
  "zvariant",
@@ -4256,7 +4317,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7074f3e50b894eac91750142016d30d0a89be8e67dbfd9704fb875825760e52d"
 dependencies = [
  "serde",
- "winnow",
+ "winnow 1.0.3",
  "zvariant",
 ]
 
@@ -4376,7 +4437,7 @@ dependencies = [
  "endi",
  "enumflags2",
  "serde",
- "winnow",
+ "winnow 1.0.3",
  "zvariant_derive",
  "zvariant_utils",
 ]
@@ -4404,5 +4465,5 @@ dependencies = [
  "quote",
  "serde",
  "syn",
- "winnow",
+ "winnow 1.0.3",
 ]