Make accessor required for table-level index defs in typescript

[joshua-spacetime]

Description of Changes

This patch contains two main changes:

1. It makes accessor a required argument for table-level index defs in typescript to align with rust.

2. It removes unsound index typing in the TypeScript bindings by splitting index data into two explicit representations:

   • indexes: declarative user config (IndexOpts) used for type inference
   • resolvedIndexes: normalized runtime metadata (UntypedIndex) derived from RawTableDefV10

   TableCacheImpl now builds index accessors from resolvedIndexes instead of re-casting indexes at runtime.

   This addressed the following comment:

   // TODO: horrible horrible horrible. we smuggle this `Array<UntypedIndex>`
   // by casting it to an `Array<IndexOpts>` as `TableToSchema` expects.
   // This is then used in `TableCacheImpl.constructor` and who knows where else.
   // We should stop lying about our types.
   

   Why?

   We were conflating two different concepts under tableDef.indexes:

   1. declared table-level index options authored by users
   2. resolved runtime index definitions (including field-level inferred indexes)

   This required unsafe casts (T['idxs'] / UntypedIndex) and made the type model unsound.

Note, (2) was largely ai assisted.

API and ABI breaking changes

Technically breaks the module api, although I believe this is the behavior that is outlined in the spec, and so the current behavior should really be considered a bug.

Expected complexity level and risk

2

Testing

Added unit tests covering the following:

1. Table-level explicit index without accessor throws.
2. Table-level duplicate accessor throws.
3. Table-level explicit accessor is accepted and used.
4. Field-level .index(...) derives accessor from the field name (displayName).

[joshua-spacetime]

@Shubham8287 has approved (1). I've added @coolreader18 for review of (2).