Schema mismatch warnings lack model context and misrepresent API response shapes

Summary

When extension models write resource data, the data-writer emits schema validation warnings that (1) don't identify which model triggered them, and (2) are caused by the extension model's Zod schema not matching the actual API response shape.

Steps to Reproduce

1. Create a droplet model and run create:

   swamp model create @stack72/digitalocean/droplet web-droplet
   swamp model method run web-droplet create --input '{"dropletName": "web-1"}'

2. Observe the warning in logs:

   19:53:43.028   warning swamp·data-writer    Resource '"state"' data does not match schema:
     'Invalid input: expected object, received null at "kernel";
      Invalid input: expected object, received null at "next_backup_window";
      Invalid option: expected one of "nyc1"|"sfo1"|... at "region"'

Expected Behavior

• The warning should identify which model and instance triggered it (e.g. swamp·data-writer·web-droplet·web-1)
• The extension model's schema should match the actual DO API response shape, not just the request shape

Actual Behavior

Three schema mismatches, all caused by the extension model's Zod schema being modeled on the request shape rather than the response shape:

1. kernel: Schema expects an object, DO API returns null (no kernel selected on the droplet)
2. next_backup_window: Schema expects an object, DO API returns null (backups not enabled)
3. region: Schema expects a string enum ("lon1"), but the DO API response returns an expanded object: {"name": "London 1", "slug": "lon1", "features": [...], ...}

The data saves correctly (via .passthrough()), so these warnings are pure noise. But they're indistinguishable from a real data corruption problem.

Impact

• With multiple models running in parallel in a workflow, there's no way to tell which model produced the warning
• Users cannot distinguish "harmless schema mismatch in the extension" from "your data is actually wrong"
• The warnings appear on every create/get operation, training users to ignore all warnings

Suggested Fix

• data-writer: Include the model name and instance name in the log context (e.g. swamp·data-writer·web-droplet·web-1)
• @stack72/digitalocean/droplet schema: Update the Zod schema to match the API response shape — kernel and next_backup_window should be nullable, region should be an object (not a string enum)

Environment

• swamp extension: @stack72/digitalocean/droplet v2026.03.05.6
• OS: macOS (Darwin 25.2.0)