generate per-component workflows; single-component output unchanged

[joshua-temple]

Problem / why

The generator must emit per-component workflow files for a manifest that declares components
while leaving single-component output byte-identical. The synthesized default component (no
components: block) keeps the existing filenames (orchestrate.yaml, promote.yaml, ...);
declared components get per-component files. This issue establishes the per-component file
scaffolding; the per-component triggers and version wiring are completed in V3.

Scope

This PR does:

• Set the multi-component generator path: fan generation out over the declared components in
  internal/generate/command.go, choosing a per-component output filename (for example
  orchestrate-api.yaml, orchestrate-web.yaml) and a component-scoped config per component.
• Keep the single-component path emitting the existing single set of files with the existing
  names, byte-identical. The default component never produces orchestrate-default.yaml.
• Confirm GeneratedFileMarker orphan detection (internal/generate/marker.go) works across
  the per-component files (it already supports multiple cascade-owned files).

This PR does NOT:

• Wire each component file's on.push.paths from component triggers, or per-component version
  math (V2 / V3 do that).
• Touch promotion file generation (P2).

Files / areas touched

• internal/generate/command.go - multi-component per-component file fan-out and filenames.
• internal/generate/generator.go - per-component config emission.
• internal/generate/marker.go - confirm multi-file orphan detection.

Tests and coverage required

• Generator unit tests: a two-component manifest emits two orchestrate files.
• A byte-stability test that single-component generated workflows are unchanged.
• actionlint-clean assertion on the generated multi-component workflows.

Acceptance criteria

• A multi-component manifest emits one orchestrate file per component.
• Single-component generated workflows are byte-identical to current output.
• Generated multi-component workflows are actionlint-clean.

Dependencies

Blocked by F1 and F2.

[joshua-temple]

Implemented and merged via #514.