[ENHANCEMENT] Add Opus 4.5 for Bedrock provider

[tejasxo]

The Opus 4.5 model has been released on Bedrock but has not yet been added to KiloCode

[TotalLag]

Would love to see this get officially added. From my testing:

1. Bedrock works if you use custom ARN for 4.5
2. Custom seems to be capped at 128k context even though the modal is capable of 200k
3. There is a high chance that Context Condensing fails