feat(templates): support Container builds in the strands-http-python template

[Hweinstock]

Problem

strands-http-python didn't support Container builds — create --template strands-python --build Container errored, and the template shipped no Dockerfile.

Changes

• Relax the --template/--build guard and add resolveRuntimeTemplateShortcut (from fix(scaffold): allow certain template values to be overriden aws/agentcore-cli#2130); --build etc. can now override a template, only --language/--framework stay locked.
• Add a filter option to FsTreeNode.fromAssetSource (from feat(templates): wire in memory to the runtime templates aws/agentcore-cli#2116).
• Strands resolver includes Dockerfile/.dockerignore only when build === "Container".
• Add Dockerfile.template + dockerignore.template to the template. The .template suffix (stripped in renderName, per fix(binary): address missing dockerfile in container agents aws/agentcore-cli#2139) avoids bun build embedding an extensionless Dockerfile as Dockerfile. — a latent bug that also affected hello-world-python-container, now fixed.
• The strands Dockerfile.template mirrors mainline's container/python/Dockerfile (templated {{entrypoint}} / {{#if enableOtel}}), minus the harness-specific git-skills install block.

Verification

Built via bun run compile:linux-x64; bun test → 2170 pass.

create --template strands-python --build Container   → build "Container", Dockerfile + .dockerignore present
create --template strands-python                     → build "CodeZip", no Dockerfile

• Container image builds, runs, and returns real streamed data on POST /invocations locally.
• CodeZip: deployed (project deploy) and invoked (aws bedrock-agentcore invoke-agent-runtime) → 200, real response.
• Container: strands container agent deployed (project deploy → CREATE_COMPLETE in us-east-1) and invoked (aws bedrock-agentcore invoke-agent-runtime → 200, real response). Note: a region whose CDK bootstrap uses a scoped exec role lacking kms:CreateGrant will fail ECR-repo creation — an account/bootstrap config matter, not a template/code issue.

Reproduce

bun install && bun test && bun run compile:linux-x64
dist/bin/agentcore-linux-x64 project create --template strands-python --build Container --name p --skip-install --skip-git
cat p/agentcore/agentcore.json | jq '.runtimes[0].build'   # "Container"
ls -A p/app/strands_agent | grep -i docker                 # Dockerfile + .dockerignore