fix: preserve resource references and map enumeration order

[benletchford]

Summary

• keep detached resources represented in their resource map while unloading shared data
• reload NIL indexed resource handles and reconnect existing master pointers
• preserve resource reference-list order for indexed enumeration

Cause

DetachResource removed the resource-map entry entirely, and indexed enumeration then sorted the remaining hash-map entries by numeric ID. Applications that enumerate and checksum resources therefore saw the wrong resource set and order.

Evidence

TaskMaker 2.2.3 now enumerates CODE and TEXT resources in their on-disk reference-list order. Its computed integrity checksum is 02C3, matching its embedded CSTR value, and startup completes without damage dialog 777.

Tests

• cargo test (2,953 passed, 3 ignored; all binary and doc tests passed)
• TaskMaker 2.2.3 scripted startup through tick 810; checksum 02C3; no damage dialog

Closes #575