feat(wasm): WASM bindings for browser use (#638)

## Summary

Add WebAssembly bindings for using the Postgres Language Server in the
browser. This enables:
- SQL parsing and linting in web applications
- Monaco editor integration with LSP support
- Schema-aware completions and hover information

## Two APIs

The package provides two independent APIs:

| API | Use Case | Import Path |
|-----|----------|-------------|
| **Workspace** | Direct parse, lint, complete, hover |
`@postgres-language-server/wasm/workspace` |
| **LanguageServer** | Full LSP JSON-RPC protocol |
`@postgres-language-server/wasm/lsp` |

### Workspace API Example

```typescript
import { createWorkspace } from '@postgres-language-server/wasm/workspace';

const workspace = await createWorkspace();
workspace.insertFile('/query.sql', 'SELECT * FROM users;');
const diagnostics = workspace.lint('/query.sql');
const completions = workspace.complete('/query.sql', 14);
```

### LanguageServer API Example

```typescript
import { createLanguageServer } from '@postgres-language-server/wasm/lsp';

const lsp = await createLanguageServer();
const responses = lsp.handleMessage({
  jsonrpc: '2.0',
  id: 1,
  method: 'initialize',
  params: { capabilities: {} }
});
```

## Implementation

- `pgls_wasm` Rust crate with Emscripten target
- `@postgres-language-server/wasm` TypeScript package
- Web worker integration for Monaco editor

## Test plan

- [x] Unit tests for Workspace API (parse, lint, complete, hover)
- [x] Unit tests for LanguageServer API (LSP messages)
- [x] E2E tests with Monaco editor via Playwright
- [x] Web worker integration tests

Author: psteinroe

.cargo/config.toml

@@ -0,0 +1,11 @@
+[target.wasm32-unknown-emscripten]
+rustflags = [
+  "-C",
+  "link-args=-sSTANDALONE_WASM=0",
+  "-C",
+  "link-args=-sERROR_ON_UNDEFINED_SYMBOLS=0",
+  "-C",
+  "link-args=-sDISABLE_EXCEPTION_CATCHING=1",
+  "-C",
+  "link-args=-sEXPORTED_FUNCTIONS=['_pgls_init','_pgls_free_string','_pgls_set_schema','_pgls_clear_schema','_pgls_insert_file','_pgls_remove_file','_pgls_lint','_pgls_complete','_pgls_hover','_pgls_parse','_pgls_version','_pgls_handle_message','_malloc','_free']",
+]

.github/workflows/pull_request.yml

@@ -241,6 +241,42 @@ jobs:
         working-directory: packages/@postgres-language-server/cli
         run: bun run test
 
+  test-wasm:
+    name: Test WASM Package
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v4
+        with:
+          submodules: true
+
+      - name: Free Disk Space
+        uses: ./.github/actions/free-disk-space
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Setup Magic Nix Cache
+        uses: DeterminateSystems/magic-nix-cache-action@main
+
+      - name: Install root JS dependencies
+        run: nix develop --command bun install
+
+      - name: Install WASM package dependencies
+        run: nix develop --command bash -c "cd packages/@postgres-language-server/wasm && bun install"
+
+      - name: Build WASM package
+        run: nix develop --command bash -c "cd packages/@postgres-language-server/wasm && bun run build"
+
+      - name: Run WASM unit tests
+        run: nix develop --command bash -c "cd packages/@postgres-language-server/wasm && bun test"
+
+      - name: Install Playwright
+        run: nix develop --command bash -c "cd packages/@postgres-language-server/wasm && bun run test:e2e:install"
+
+      - name: Run WASM e2e tests
+        run: nix develop --command bash -c "cd packages/@postgres-language-server/wasm && bun run test:e2e"
+
   codegen:
     name: Check Codegen
     runs-on: ubuntu-22.04

.gitignore

@@ -33,6 +33,20 @@ crates/pgt_treesitter_grammar/src/grammar.json
 crates/pgt_treesitter_grammar/src/node-types.json
 crates/pgt_treesitter_grammar/src/parser.c
 crates/pgt_treesitter_grammar/src/parser.c.codex-session-id
+crates/pgls_treesitter_grammar/src/grammar.json
+crates/pgls_treesitter_grammar/src/node-types.json
+crates/pgls_treesitter_grammar/src/parser.c
+
+# WASM package build artifacts
+crates/pgls_wasm/dist/
+packages/@postgres-language-server/wasm/wasm/pgls.js
+packages/@postgres-language-server/wasm/wasm/pgls.wasm
+
+# Playwright
+playwright-report/
+test-results/
 .codex-session-id
 
 site/
+
+biome-main/

Cargo.lock

@@ -37,7 +37,7 @@ rayon                    = "1.10.0"
 regex                    = "1.11.1"
 rustc-hash               = "2.0.0"
 schemars                 = { version = "0.8.22", features = ["indexmap2", "smallvec"] }
-serde                    = "1.0.195"
+serde                    = { version = "1.0.195", features = ["rc"] }
 serde_json               = "1.0.114"
 similar                  = "2.6.0"
 slotmap                  = "1.0.7"
@@ -82,7 +82,7 @@ pgls_plpgsql_check          = { path = "./crates/pgls_plpgsql_check", version =
 pgls_query                  = { path = "./crates/pgls_query", version = "0.0.0" }
 pgls_query_ext              = { path = "./crates/pgls_query_ext", version = "0.0.0" }
 pgls_query_macros           = { path = "./crates/pgls_query_macros", version = "0.0.0" }
-pgls_schema_cache           = { path = "./crates/pgls_schema_cache", version = "0.0.0" }
+pgls_schema_cache           = { path = "./crates/pgls_schema_cache", version = "0.0.0", default-features = false }
 pgls_splinter               = { path = "./crates/pgls_splinter", version = "0.0.0" }
 pgls_statement_splitter     = { path = "./crates/pgls_statement_splitter", version = "0.0.0" }
 pgls_suppressions           = { path = "./crates/pgls_suppressions", version = "0.0.0" }
@@ -92,6 +92,7 @@ pgls_tokenizer              = { path = "./crates/pgls_tokenizer", version = "0.0
 pgls_treesitter             = { path = "./crates/pgls_treesitter", version = "0.0.0" }
 pgls_treesitter_grammar     = { path = "./crates/pgls_treesitter_grammar", version = "0.0.0" }
 pgls_typecheck              = { path = "./crates/pgls_typecheck", version = "0.0.0" }
+pgls_wasm                   = { path = "./crates/pgls_wasm", version = "0.0.0" }
 pgls_workspace              = { path = "./crates/pgls_workspace", version = "0.0.0" }
 pgls_workspace_macros       = { path = "./crates/pgls_workspace_macros", version = "0.0.0" }