[TW-4797] Add hosted templates and workflows support

[sourcesoft]

Summary

This PR adds full hosted templates and workflows support to the CLI.

It introduces dedicated template and workflow command groups for app-scoped and grant-scoped hosted resources, integrates hosted-template rendering into nylas email send, updates the docs, and expands unit/integration coverage.

What changed

Hosted templates and workflows

• Added domain models and ports for hosted templates, template rendering, and workflows.
• Implemented HTTP adapter support for app-scoped and grant-scoped template/workflow CRUD and render operations.
• Added mock and demo client implementations for the new APIs.
• Wired new top-level CLI groups:
  • nylas template list|show|create|update|delete|render|render-html
  • nylas workflow list|show|create|update|delete
• Added shared CLI helpers for scope resolution, JSON file loading, and grant identifier handling.

Hosted-template email send integration

• Extended nylas email send to support hosted templates directly with:
  • --template-id
  • --template-scope
  • --template-grant-id
  • --template-data
  • --template-data-file
  • --render-only
  • --template-strict
• Ensured hosted-template rendering also works on the GPG send path.
• Added render-only preview support without requiring an unrelated send grant for app-scoped previews.

Grant identifier correctness

• Fixed grant-scoped identifier resolution so explicit email identifiers are resolved from local grant state instead of silently falling back to NYLAS_GRANT_ID.
• Added isolated integration harness support to seed a temporary encrypted local grant store so email-based grant resolution is tested correctly.

Documentation

Updated command docs for the new CLI surface and hosted-template send flow in:

• docs/COMMANDS.md
• docs/commands/email.md
• docs/commands/templates.md
• docs/commands/workflows.md

Testing

Added/expanded coverage

• Adapter unit tests for hosted template/workflow operations.
• CLI unit tests for template/workflow commands and hosted-template send behavior.
• Integration tests for:
  • template CRUD/list/render/render-html
  • workflow CRUD/list
  • app scope and grant scope
  • file-backed inputs
  • render-only hosted-template preview
  • hosted-template send paths
  • self-send hosted-template round trip
  • email-based grant identifier resolution

Verification

• make ci-full

This passed locally, including:

• formatting
• vet
• lint
• unit tests
• race tests
• security scan
• vuln check
• build
• integration tests
• Air integration tests
• test cleanup

Notes

A small set of existing test files outside the feature area were also updated to resolve pre-existing lint/staticcheck blockers uncovered while getting make ci-full green. Those changes are mechanical test-quality fixes needed for the full pipeline to pass.

[chatgpt-codex-connector]

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[qasim-nylas]

LGTM 👍