fix(ts-sdk): Add primaryKey() and index() to SumBuilderImpl and SumColumnBuilder (#4389)

## Summary

- Codegen unconditionally emits `.primaryKey()` on all primary key
columns, including enum types
- `SumBuilderImpl` (used for **all** object-form enums via
`__t.enum("Name", { ... })`) only implemented `Defaultable` and
`Nameable` — not `PrimaryKeyable` or `Indexable`
- This causes a runtime `TypeError: SC.primaryKey is not a function`
whenever an enum type is used as a primary key column

## Fix

Add `Indexable` and `PrimaryKeyable` interfaces and their methods to:
- `SumBuilderImpl` (the base class for all enum type builders)
- `SumColumnBuilder` (the column builder returned by `SumBuilderImpl`
methods)

This matches the existing pattern already present in
`SimpleSumBuilderImpl` and `SimpleSumColumnBuilder`.

## Why SumBuilderImpl and not just SimpleSumBuilderImpl?

Codegen always generates object-form enums:
```typescript
export const PlatformModuleType = __t.enum("PlatformModuleType", {
  Standard: __t.unit,
  Control: __t.unit,
});
```

The runtime dispatch in `type_builders.ts` (line ~3656) routes
object-form enums to `SumBuilder` (backed by `SumBuilderImpl`), never to
`SimpleSumBuilder`. So `SimpleSumBuilderImpl`'s existing
`primaryKey()`/`index()` methods are effectively dead code for codegen
output.

## Test plan

- [x] Verify enum types used as primary keys no longer throw `TypeError:
SC.primaryKey is not a function`
- [ ] Verify existing `SimpleSumBuilderImpl`/`SimpleSumColumnBuilder`
behavior is unchanged (subclass overrides still work)


🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Zeke Foppa <196249+bfops@users.noreply.github.com>

Author: 3 people

crates/bindings-typescript/src/lib/type_builders.ts

@@ -1568,7 +1568,9 @@ class SumBuilderImpl<Variants extends VariantsObj>
   extends TypeBuilder<EnumType<Variants>, VariantsToSumType<Variants>>
   implements
     Defaultable<EnumType<Variants>, VariantsToSumType<Variants>>,
-    Nameable<EnumType<Variants>, VariantsToSumType<Variants>>
+    Nameable<EnumType<Variants>, VariantsToSumType<Variants>>,
+    Indexable<EnumType<Variants>, VariantsToSumType<Variants>>,
+    PrimaryKeyable<EnumType<Variants>, VariantsToSumType<Variants>>
 {
   readonly variants: Variants;
   readonly typeName: string | undefined;
@@ -1673,6 +1675,33 @@ class SumBuilderImpl<Variants extends VariantsObj>
   ): SumColumnBuilder<Variants, SetField<DefaultMetadata, 'name', Name>> {
     return new SumColumnBuilder(this, set(defaultMetadata, { name }));
   }
+  index(): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'indexType', 'btree'>
+  >;
+  index<N extends NonNullable<IndexTypes>>(
+    algorithm: N
+  ): SumColumnBuilder<Variants, SetField<DefaultMetadata, 'indexType', N>>;
+  index(
+    algorithm: IndexTypes = 'btree'
+  ): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'indexType', IndexTypes>
+  > {
+    return new SumColumnBuilder(
+      this,
+      set(defaultMetadata, { indexType: algorithm })
+    );
+  }
+  primaryKey(): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'isPrimaryKey', true>
+  > {
+    return new SumColumnBuilder(
+      this,
+      set(defaultMetadata, { isPrimaryKey: true })
+    );
+  }
 }
 
 export const SumBuilder: {
@@ -3273,7 +3302,9 @@ export class SumColumnBuilder<
   extends ColumnBuilder<EnumType<Variants>, VariantsToSumType<Variants>, M>
   implements
     Defaultable<EnumType<Variants>, VariantsToSumType<Variants>>,
-    Nameable<EnumType<Variants>, VariantsToSumType<Variants>>
+    Nameable<EnumType<Variants>, VariantsToSumType<Variants>>,
+    Indexable<EnumType<Variants>, VariantsToSumType<Variants>>,
+    PrimaryKeyable<EnumType<Variants>, VariantsToSumType<Variants>>
 {
   default(
     value: EnumType<Variants>
@@ -3294,6 +3325,33 @@ export class SumColumnBuilder<
       set(this.columnMetadata, { name })
     );
   }
+  index(): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'indexType', 'btree'>
+  >;
+  index<N extends NonNullable<IndexTypes>>(
+    algorithm: N
+  ): SumColumnBuilder<Variants, SetField<DefaultMetadata, 'indexType', N>>;
+  index(
+    algorithm: IndexTypes = 'btree'
+  ): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'indexType', IndexTypes>
+  > {
+    return new SumColumnBuilder(
+      this.typeBuilder,
+      set(this.columnMetadata, { indexType: algorithm })
+    );
+  }
+  primaryKey(): SumColumnBuilder<
+    Variants,
+    SetField<DefaultMetadata, 'isPrimaryKey', true>
+  > {
+    return new SumColumnBuilder(
+      this.typeBuilder,
+      set(this.columnMetadata, { isPrimaryKey: true })
+    );
+  }
 }
 
 export class SimpleSumColumnBuilder<