Add Phase 1 SQL support with DataFusion and Substrait

Implements end-to-end SQL query pipeline for simple SELECT queries:

Compile-time: MergedSelectionMap → DataFusion LogicalPlan → Substrait binary
Runtime: Substrait plan → isograph-server execution → Arrow IPC response

New components:
- crates/sql_network_protocol: NetworkProtocol impl; LogicalPlan builder and
  Substrait serialization; parses SQL schema into Isograph's type model
- crates/sql_lang_types, crates/sql_schema_parser: SQL-specific language types
  and DDL parser
- crates/isograph_server: Axum HTTP server with /query endpoint
- demos/sqlite-demo: end-to-end Vite+React demo using Star Wars planets SQLite
- test-fixtures/databases: SQLite schema and init scripts for Phase 1–3
- E2E Playwright tests for the full pipeline

Type system: widen NetworkResponseObject from branded-key mapped type to plain
string index signature so SQL-generated types (e.g. { id: number, name: string })
satisfy the constraint without @ts-ignore. SQL numeric IDs accepted via
id?: DataId | number. Zero breaking change for existing GraphQL code.

Compiler: add readonly modifiers and field-name quoting to SQL-generated
raw_response_type.ts files.

Build fixes: update swc workspace deps for serde 1.0.220+ compatibility,
fix clippy needless_return, add protoc to CI for substrait code generation,
update pnpm lockfile, fix prettier and oxlint issues.

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

Author: edmondop

.github/workflows/ci.yml

@@ -240,6 +240,8 @@ jobs:
         with:
           toolchain: stable
           components: clippy
+      - name: Install protoc
+        run: sudo apt-get update && sudo apt-get install -y protobuf-compiler
       - name: Run cargo clippy
         run: cargo clippy
 
@@ -253,6 +255,8 @@ jobs:
         with:
           toolchain: stable
           components: rustfmt
+      - name: Install protoc
+        run: sudo apt-get update && sudo apt-get install -y protobuf-compiler
       - name: Run cargo test
         run: cargo test