Remove dead commented-out TODO code blocks from all source files

[DaraOladapo]

Description

Every source file contains large #region TODO blocks of commented-out code for GenericModel<T> variants that were never finished. Across all five files this amounts to ~850 lines of dead code that adds noise and maintenance burden without providing value.

Affected Files

File	Approx. commented lines
Get.cs	~165
Post.cs	~185
Put.cs	~185
Patch.cs	~185
Delete.cs	~165

Decision Required

1. Implement the GenericModel<T> variants properly and ship them (tracked separately), then delete the commented blocks — or —
2. Delete the commented blocks outright; git history preserves them if they're ever needed again.

Either way, the commented blocks should not remain in the shipping source.

Acceptance Criteria

• No #region TODO comment blocks remain in any .cs file in the library project
• If implementing the variants, they are covered by tests before the region is removed