💥 feat(sdk): remove usage of anyhow from public error types

[chris-olszewski]

What was changed

• Switch ApplicationFailure to be backed by boxed errors
• Switch WorkflowError to be backed by boxed errors
• WorkflowContext::force_task_fail now works with boxed errors instead of anyhow
• Added helper for constructing a WorkflowTermination from ApplicationFailure (allows ? to work well in workflow code)
• Cleaned up some examples/tests that still had extra anyhow wrapping

These are technically breaking changes, but most code should continue to work without issue as anyhow::Error implements Into<Box<dyn Error + Send + Sync>>

Each commit is reviewable on its own.

Why?

Reduce our usage of anyhow in public facing APIs

Checklist

1. Closes N/A

2. How was this tested:
   Existing tests

3. Any docs updates needed?
   Once released we can update docs to no longer have ApplicationFailure::new(anyhow!("boom"))

[Sushisource]

Niiiice!

Maybe update agents.md and/or the readme with info that we shouldn't depend on anyhow in public API of the SDK?

[github-actions]

Opengrep — new findings

Severity	Location	Rule	Message
ERROR	crates/protos/protos/api_upstream/.github/workflows/create-release.yml:25	security.gha.missing-explicit-permissions-temporal	No explicit GITHUB_TOKEN permissions found at the workflow or job level. Add a permissions: block at the workflow root (applies to all jobs) or per job with least privilege (e.g., contents: read and only specific writes like pull-requests: write if needed).
ERROR	crates/protos/protos/api_upstream/.github/workflows/create-release.yml:30	security.gha.missing-explicit-permissions-temporal	No explicit GITHUB_TOKEN permissions found at the workflow or job level. Add a permissions: block at the workflow root (applies to all jobs) or per job with least privilege (e.g., contents: read and only specific writes like pull-requests: write if needed).
ERROR	crates/protos/protos/api_upstream/.github/workflows/create-release.yml:99	security.gha.missing-explicit-permissions-temporal	No explicit GITHUB_TOKEN permissions found at the workflow or job level. Add a permissions: block at the workflow root (applies to all jobs) or per job with least privilege (e.g., contents: read and only specific writes like pull-requests: write if needed).
ERROR	crates/protos/protos/api_upstream/.github/workflows/trigger-api-go-update.yml:16	security.gha.missing-explicit-permissions-temporal	No explicit GITHUB_TOKEN permissions found at the workflow or job level. Add a permissions: block at the workflow root (applies to all jobs) or per job with least privilege (e.g., contents: read and only specific writes like pull-requests: write if needed).

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