Phase 6 (#1075): Route fleet / launcher / CLI callers through Gremlin

[xbrianh]

Part of #1075. Depends on #1093 (Phase 4). Can be worked in parallel with #1094 (Phase 5).

What

The remaining external callers don't run stages; they read or write state for orchestration purposes (listing, landing, resuming). They should hold a Gremlin and access gremlin.state.* directly rather than calling StateData.load, build_state, etc.

File	Currently uses	Route to
fleet/land.py	landable_shape, resolve_artifact_dir, StateData, build_state	Gremlin.load(gremlin_id) → gremlin.state.*
fleet/views.py	StateData for status reads	Gremlin.load(gremlin_id).state.*
executor/run.py	StateData.load, resolve_artifact_dir, resolve_state_file	Already uses Gremlin; remove residual direct calls, access via gremlin.state.*
launcher.py	StateData, validate_gremlin_id	Gremlin constructor + gremlin.state.*
cli/resume.py	validate_gremlin_id	Gremlin.validate_id() or launcher.resume()
utils/proc.py	State under TYPE_CHECKING only	Change type annotation to Gremlin

Add a Gremlin.load(gremlin_id) classmethod so callers that only need to inspect persisted state don't have to call StateData.load directly — they get a Gremlin with gremlin.state pre-populated from disk. Remove state.py imports from each file.

Files

• gremlins/fleet/land.py
• gremlins/fleet/views.py
• gremlins/executor/run.py
• gremlins/launcher.py
• gremlins/cli/resume.py
• gremlins/utils/proc.py
• gremlins/executor/gremlin.py (new load classmethod)