Implement AWS Bedrock AI Connector

[LinceMathew]

Summary

• Adds AWS Bedrock as a selectable provider in git-lrc's local connector-management UI (lrc ui), matching the Bedrock support already shipped in LiveReview's own AIProviders page.
• Demo: https://youtu.be/zVf2O9z_370

Linked Issue

No tracked issue — implemented directly per request to bring git-lrc's local conReview's Bedrock connector support.

Validation

• go build ./... — clean
• gofmt -l . — clean on all touched Go files
• node --check on all touched JS files (ui-connectors.js, ConnectorFormPage.js, providers.js) — clean
• Did not run a live click-through of the UI in this session — recommend manual fetch-models/save flow before merge (see checklist below).

Checklist

• This PR fulfills an agreed issue.
• I kept the change narrow and scoped.
• I ran the most specific relevant validation and described it above.
• If I changed behavior, I called that out clearly in this PR.
• If I touched UI, I attached a GIF or video walkthrough. This is required.
• If I changed storage/ responsibilities, I updated storage/storage_statutus-doc. (N/A — no storage/ files touched)
• If I changed network/ responsibilities, I updated network/network_status.md and ran make check-status-doc. (N/A — no network/ files touched)
• If this change touches security, disclosure flow, credentials, storage, network behavior, or remote data handling, I reviewed SECURITY.md and updated related documentation if needed.