feat: add AWS PRM user-agent attribution for Bedrock calls

[blinkagent]

Adds config.WithAppID to the AWS SDK config used for Bedrock API calls, setting the AWS Partner Revenue Measurement (PRM) user-agent attribution on every Bedrock request.

This is the AI Bridge counterpart to coder/coder#23138, which covers the Terraform provisioner path. Together, they ensure all AWS API calls made by Coder — both workspace infrastructure (Terraform) and LLM inference (Bedrock) — include PRM attribution in the user-agent header.

How it works

• withAWSBedrockOptions() now passes config.WithAppID("APN_1.1/pc_cdfmjwn8i6u8l9fwz8h82e4w3$") to config.LoadDefaultConfig
• The AWS SDK appends this to the user-agent header on every Bedrock API call
• Only affects Bedrock calls — OpenAI and direct Anthropic API calls are unaffected (they don't use the AWS SDK)

Notes

• Same obfuscation consideration as the coder/coder PR — the product code is hardcoded in source. It may be worth injecting via -ldflags -X at build time, though it is a public identifier on the AWS Marketplace listing.

References

• Companion PR: feat: add AWS PRM user-agent attribution for partner revenue tracking coder#23138
• AWS SDK Application ID docs
• AWS PRM Automated User Agent (partner login required)