feat: add project aware trace support for runtime

[nborges-aws]

Description

Adds project-aware runtime traces through agentcore project traces runtime list|get. The commands resolve a runtime and target to its physical id and region, thendelegates to the existing shared observability trace handlers.

This PR builds on the project observability setup introduced in PR #2271. Also adds tests exercising routing and updates the readMe with project trace examples.

agentcore project traces runtime list
agentcore project traces runtime list --name FooRuntime --target production --since 30m
agentcore project traces runtime get <traceId> --name FooRuntime --output trace.json

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

Manual testing, plus added tests exercising runtime resolution, explicit target/qualifier selection, and region propagation.

• bun run test (3170 pass, 0 fail)
• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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[agentcore-devx-automation]

AgentCore Harness Review

Verdict: Looks good

Nice, focused addition that mirrors the existing project log runtime handler almost exactly.

• Reuses createListTracesHandler / createGetTraceHandler and the shared runtimeLogGroup / DEFAULT_ENDPOINT_QUALIFIER helpers so behavior stays consistent with runtime traces.
• resolveProjectRuntime correctly pins the region from deployed.target.region (rather than trusting the backend echo) — matches the note in ProjectManager.resolveDeployedResource.
• Command path (/agentcore/project/traces/runtime/{list,get}) satisfies the telemetry commandPathSchema, so cli.command_run events emitted by the router will still validate — no extra telemetry wiring needed.
• Tests use tmpdir + a real ProjectSpecSchema-parsed project and only stub at the true boundaries (ProjectBackend, core.observability), which matches the workspace guidance on mocking.
• README tree and examples are updated to match the new subcommand.

Minor consistency observation (non-blocking): the imperative runtime traces router is built via createTracesHandler({ description, list, get }), while createProjectRuntimeTracesHandler constructs new Router("runtime", ...).handler(list).handler(get) inline. Functionally equivalent, but you could route through createTracesHandler for symmetry with runtime/traces/index.tsx.

Nothing here needs to change before merge.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.93%. Comparing base (b8b8877) to head (fb04f87).

Additional details and impacted files

@@              Coverage Diff              @@
##           project-logs    #2273   +/-   ##
=============================================
  Coverage         96.93%   96.93%           
=============================================
  Files               567      569    +2     
  Lines             39231    39287   +56     
=============================================
+ Hits              38027    38083   +56     
  Misses             1204     1204           

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