fix: move AWS Bedrock IAM credentials to secret installation parameters [AIS-296]

[Tyler Pina (tylerpina)]

AIS-296

Summary

• Adds a Contentful Function (functions/bedrock-proxy.ts) that reads accessKeyId, secretAccessKey, and region server-side via context.appInstallationParameters and proxies InvokeModel requests to AWS Bedrock using AWS SigV4 signing — credentials never touch browser-side code
• Wires up contentful-app-manifest.json with an App Action (bedrockProxyAction) so the Dialog location calls the function via sdk.cma.appActionCall.createWithResponse instead of instantiating BedrockClient/BedrockRuntimeClient in the browser
• Deletes the browser-side src/utils/aiApi client (the actual SAST finding) and removes accessKeyId/secretAccessKey from browser-readable state; the config AccessKey component becomes write-only (admin can set new credentials but can't read stored values back); Model becomes a static list rather than live-validating against AWS with the credentials
• Flattens the installation parameters to top-level scalars so a Secret-typed param validates (a Secret opts the whole params object into strict scalar-only validation — nested brandProfile is flattened, enabledFeatures is JSON-encoded into a Symbol string and rehydrated in the reducer/hooks)

Notes

• This PR is the code half of the fix. The AppDefinition Secret type declaration for accessKeyId and secretAccessKey must be applied separately before deploy — without it, the credentials are still plaintext in the browser even after this code lands.
• SigV4 signing service name is bedrock, not bedrock-runtime — the latter is only the endpoint host prefix. Signing with the wrong name yields InvalidSignatureException on every call. Covered by a regression test in functions/bedrock-proxy.spec.ts.
• UX change: generation is no longer streamed token-by-token; the full response is revealed at once (a skeleton loader shows while generating). Streaming was architecturally incompatible with Contentful Functions' single-response model.
• Model availability checking (which called AWS ListFoundationModels + InvokeModelCommand using the browser-side credentials) is removed. The model list is now static.
• On merge: update the status column for row 273 in the Cypress SAST findings spreadsheet and keep the Jira ticket in sync.

Test plan

• npx vitest run passes (56/56)
• npm run lint passes (0 errors, 0 warnings)
• npx tsc --noEmit clean
• npm run build:functions emits build/functions/bedrock-proxy.js
• Manual — AppDefinition update: Declare accessKeyId and secretAccessKey as "type": "Secret" (and remaining installation fields as Symbol) via CMA or Contentful UI for the Bedrock app definition
• Manual: After AppDefinition update, verify sdk.parameters.installation.accessKeyId returns *** in browser console
• Manual: Deploy function bundle (npm run deploy:test) and confirm App Action invocation succeeds end-to-end in a test space

Generated with Claude Code

[wiz-inc-38d59fb8d7]

Wiz Scan Summary

Scanner	Findings
Vulnerabilities	-
Sensitive Data	-
Secrets	-
IaC Misconfigurations	-
SAST Findings	1
Software Management Findings	-
Total	1

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