refactor: always use native Snyk Code workflow

[fsargent]

Description

Remove the remaining legacy CLI dispatch branch from the code-client-go workflow. The code.test workflow now always records implementation=native, registers the SCLE auth URL when needed, and runs code_workflow.EntryPointNative directly.

This also removes the native/consistent-ignores feature-flag gate from Init, deletes the EntryPointLegacy wrapper, updates tests that previously exercised the legacy fallback, and updates README workflow documentation.

Checklist

• Tests updated and all runnable tests succeed
• Linted
• README.md updated, if user-facing

Validation run locally:

• make format
• go mod tidy
• go build ./...
• go test -cover ./...
• go test ./pkg/code ./internal/commands/code_workflow
• gofmt -w -l -e pkg/code/code.go pkg/code/code_test.go
• .bin/golangci-lint run --fix ./pkg/code/... ./internal/commands/code_workflow/...

Known local validation blocker:

• make generate could not complete because scripts/download-test-api.py requires GITHUB_PAT to be set.

🚨 After having merged, please update the snyk-ls and CLI go.mod to pull in latest client.

[fsargent]

• refactor: always use native Snyk Code workflow #160 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add the label merge-queue to this PR to add it to the merge queue.

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.