feat(sdk): add ContainerProvider and auto-deploy

[retr0h]

• ContainerProvider — New typed SDK wrapper (pkg/sdk/orchestrator/container_provider.go) that executes all provider operations (host, mem, load, disk, command, ping, DNS) inside Docker containers via the RuntimeTarget interface. Provides full type safety with Go generics (run[T]/runScalar[T] helpers).
• Auto-deploy — DockerTarget.Prepare() automatically downloads the osapi binary from GitHub releases into the container on first ExecProvider call using sync.Once. Supports WithOSAPIBinaryURL for custom URLs and WithOSAPIBinarySkip when the binary is pre-baked into the image.
• Platform detection refactor — Extracted platform detection from internal/agent/factory.go into a shared pkg/sdk/platform package so both the agent and SDK can reuse it.
• Provider registry refactor — Moved buildProviderRegistry() from cmd/provider_run.go into its own file (cmd/provider_run_registry.go) and made NewParams optional for parameterless providers.
• Example rewrite — Expanded container-targeting.go to exercise every read-only provider, command exec, error handling, and a deliberately-failing task.

[github-actions]

Thank you for contributing to this project! 😊🕹️

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@           Coverage Diff            @@
##             main     #254    +/-   ##
========================================
  Coverage   99.94%   99.94%            
========================================
  Files         224      227     +3     
  Lines        9431     9587   +156     
========================================
+ Hits         9426     9582   +156     
  Misses          3        3            
  Partials        2        2            

Files with missing lines	Coverage Δ
internal/agent/factory.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/container_provider.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/deploy.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/docker_target.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/options.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/plan.go	100.00% <100.00%> (ø)
pkg/sdk/orchestrator/plan_in.go	100.00% <100.00%> (ø)
pkg/sdk/platform/platform.go	100.00% <100.00%> (ø)

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