feat: add context7 template

[phala-agent]

Summary

• Add a Context7 prebuilt template for the official @upstash/context7-mcp@2.3.0 package.
• Expose stateless HTTP transport on port 18080 with /ping for smoke checks and /mcp for Streamable HTTP MCP clients.
• Add upstream icon from upstash/context7 public/context7-icon.svg.

Upstream

• Repository: https://github.com/upstash/context7
• Template files: templates/prebuilt/context7/docker-compose.yml, templates/prebuilt/context7/README.md
• Icon: templates/icons/context7.svg

Environment

• Required env vars: none
• Optional env vars: CONTEXT7_API_URL, RESOURCE_URL, AUTH_SERVER_URL
• Client-side Context7 API keys are documented as MCP request headers, so the template stores no real secret values.

Validation

• python3 templates/validate.py ✅
• git diff --check origin/main...HEAD ✅
• docker compose -f templates/prebuilt/context7/docker-compose.yml config >/dev/null ✅
• Static audit ✅: README coverage, unique config id, no host bind mounts, no env_file, no privileged/host network, no real secret literals, icon file present.

Phala Cloud smoke

• Profile/workspace: hermes-admin-cvm-check / h4x's projects
• Deploy command: phala deploy --profile hermes-admin-cvm-check --name auto-template-test-context7-0524-021840 --compose sdks/templates/prebuilt/context7/docker-compose.yml --instance-type tdx.small --wait --no-public-logs --no-public-sysinfo --json
• CVM UUID: 829bc374-d12c-4933-8d8a-895e0047dc2d
• App ID: 1c8b36ae88c316a79401e9d840fc8bb2bdf68d1e
• Container: dstack-context7-1 reached running and healthy.
• HTTP smoke: GET /ping returned HTTP 200 with {"status":"ok","message":"pong"}.
• MCP route check: GET /mcp returned HTTP 405 with upstream JSON-RPC message Server does not support GET requests, confirming the route is live for Streamable HTTP POST clients.
• Cleanup: phala cvms delete --profile hermes-admin-cvm-check 829bc374-d12c-4933-8d8a-895e0047dc2d --force --json returned success; follow-up lookup returned The requested CVM was not found.

cc @Marvin-Cypher for review if formal reviewer request is unavailable.

[phala-agent]

cc @Marvin-Cypher for review.

[Leechael]

@phala-agent Duplicated? https://github.com/Phala-Network/phala-cloud/tree/main/templates/prebuilt/context7-mcp

[Marvin-Cypher]

Reviewed template files, compose config, config validation, and stale path/risk scans. Checks are passing.