add tree-sitter syntax highlighting via dart:ffi

Vendor libtree-sitter.so (v0.26.8, wasmtime 44.0 statically linked)
and call its C API through dart:ffi. Grammar WASM files are loaded by
tree-sitter's embedded wasmtime engine via ts_wasm_store_load_language.

48 grammars compiled with tree-sitter build --wasm, 48 highlight
queries (42 from upstream repos, 6 written in-house for comment,
erlang, gdscript, gitignore, hcl, hlsl, swift). SQLite grammar
replaces full SQL (974K-line parser exhausted RAM at compile time).

Removes wasm_run and wasm_run_flutter — they downloaded a 22 MB
binary from GitHub at first launch, violating the no-network-on-
default-launch-path policy.

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

app/pubspec.yaml

@@ -78,6 +78,9 @@ flutter:
     - assets/logo/clide-logo-256.png
     - assets/logo/clide-logo-512.png
     - assets/logo/clide-logo-1024.png
+    # Tree-sitter WASM grammars and highlight queries.
+    - assets/grammars/
+    - assets/queries/
 
   # Bundled fonts. OFL-licensed; license files live alongside each.
   #