[Repo Assist] Perf: cache FullName, BaseType and GetInterfaces in TargetTypeDefinition (#485)

🤖 *This is an automated PR from Repo Assist, an AI assistant for this
repository.*

## Summary

`TargetTypeDefinition.FullName`, `BaseType`, and `GetInterfaces()` each
compute their result from immutable input data
(`inp.Namespace`/`inp.Name`, `inp.Extends`, `inp.Implements`) but were
recomputed on every call — allocating new strings/arrays and re-running
type resolution each time.

For large type providers with many types (e.g. SwaggerProvider), where
the F# compiler queries these properties many times per type during
type-checking, this saves repeated allocations and type-resolution work.

### Changes

| Property | Before | After |
|---|---|---|
| `FullName` | String concatenation every call | Cached `lazy` —
computed once, same `string` returned thereafter |
| `BaseType` | `txILType` (type-resolution) every call | Cached `lazy` —
resolved once |
| `GetInterfaces()` | `Array.map txILType` (allocates new `Type[]`)
every call | Cached `lazy` — resolved and allocated once |

All three caches use F# `lazy` which defaults to
`LazyThreadSafetyMode.ExecutionAndPublication`, so concurrent
first-access from multiple F# compiler threads is safe.

This is complementary to PR #471 (which cached member-wrapper arrays)
and does not touch the thread-safety areas being addressed by PRs
#482/#483.

## Test Status

```
Passed!  - Failed: 0, Passed: 117, Skipped: 0, Total: 117 (net8.0)
```

All 117 pre-existing tests pass. The `netstandard2.0` build target ran
OOM on the CI machine (infrastructure issue, not caused by this change —
the same issue affects master); the `net8.0` build and tests both pass
cleanly.




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---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

src/ProvidedTypes.fs

@@ -7982,25 +7982,35 @@ namespace ProviderImplementation.ProvidedTypes
         let propDefs    = lazy (inp.Properties.Entries |> Array.map (txILPropertyDef this))
         let nestedDefs  = lazy (inp.NestedTypes.Entries |> Array.map (asm.TxILTypeDef (Some (this :> Type))))
 
+        // Cache derived properties that are computed from immutable input data.
+        // The F# compiler may call FullName, BaseType and GetInterfaces() many times per type
+        // during type-checking; caching avoids repeated string allocations and type-resolution work.
+        let fullName =
+            lazy (
+                match declTyOpt with
+                | None ->
+                    match inp.Namespace with
+                    | UNone -> inp.Name
+                    | USome nsp -> nsp + "." + inp.Name
+                | Some declTy ->
+                    declTy.FullName + "+" + inp.Name)
+
+        let baseType = lazy (inp.Extends |> Option.map (txILType (gps, [| |])) |> Option.toObj)
+
+        let interfaces = lazy (inp.Implements |> Array.map (txILType (gps, [| |])))
+
         do this.typeImpl <- this
         override __.Name = inp.Name
         override __.Assembly = (asm :> Assembly)
         override __.DeclaringType = declTyOpt |> Option.toObj
         override __.MemberType = if isNested then MemberTypes.NestedType else MemberTypes.TypeInfo
         override __.MetadataToken = inp.Token
 
-        override __.FullName =
-            match declTyOpt with
-            | None ->
-                match inp.Namespace with
-                | UNone -> inp.Name
-                | USome nsp -> nsp + "." + inp.Name
-            | Some declTy ->
-                declTy.FullName + "+" + inp.Name
+        override __.FullName = fullName.Value
 
         override __.Namespace = inp.Namespace |> StructOption.toObj
-        override __.BaseType = inp.Extends |> Option.map (txILType (gps, [| |])) |> Option.toObj
-        override __.GetInterfaces() = inp.Implements |> Array.map (txILType (gps, [| |]))
+        override __.BaseType = baseType.Value
+        override __.GetInterfaces() = interfaces.Value
 
         override __.GetConstructors(bindingFlags) =
             ctorDefs.Force() |> Array.filter (canBindConstructor bindingFlags)