feat(dictionary): add Hachidori backend support

- Add backend selection, setup gating, Anki integration, and external host support
- Add launcher flags, documentation, packaging, and focused tests
- Open on-demand overlay modals on the first attempt

vendor/hachidori/third_party/hoshidicts/.gitmodules

@@ -0,0 +1,24 @@
+[submodule "external/utfcpp"]
+	path = external/utfcpp
+	url = https://github.com/nemtrif/utfcpp.git
+[submodule "external/glaze"]
+	path = external/glaze
+	url = https://github.com/stephenberry/glaze
+[submodule "external/zstd"]
+	path = external/zstd
+	url = https://github.com/facebook/zstd.git
+[submodule "external/unordered_dense"]
+	path = external/unordered_dense
+	url = https://github.com/martinus/unordered_dense.git
+[submodule "external/xxHash"]
+	path = external/xxHash
+	url = https://github.com/Cyan4973/xxHash.git
+[submodule "external/libdeflate"]
+	path = external/libdeflate
+	url = https://github.com/ebiggers/libdeflate.git
+[submodule "external/utf8proc"]
+	path = external/utf8proc
+	url = https://github.com/JuliaStrings/utf8proc.git
+[submodule "external/kanji-processor"]
+	path = external/kanji-processor
+	url = https://github.com/yomidevs/kanji-processor.git