[ctawiah]

Context

Provider profile adapters must preserve activation metadata while updating selected instructions.

What changes

• Add Cursor, Copilot, agents Markdown, and Claude Markdown profiles.
• Support whole bodies, sections, and LaunchDarkly marker regions.
• Preserve front matter and unknown metadata.
• Store fixtures under neutral names and materialize real paths in temporary directories.

markers[id="refunds"].body

Design notes

• Provider formats are explicit adapter choices.
• Checked-in fixture names cannot activate a coding tool.

Review focus

• Does each update preserve activation metadata?
• Are malformed or nested marker ranges rejected?

Verification

• make build
• go test ./...
• Repository lint
• Relevant race tests

Related changes

1. ctawiah/sync-projection-core-3bbf: projection and problem core
2. ctawiah/sync-reference-core-3bbf: reference registry and Markdown
3. ctawiah/sync-structured-adapters-3bbf: structured adapters
4. This PR: provider profiles
5. ctawiah/sync-python-adapter-3bbf: Python adapter
6. ctawiah/sync-typescript-adapters-3bbf: TypeScript and JavaScript adapters
7. ctawiah/sync-descriptor-storage-3bbf: descriptor storage
8. ctawiah/sync-source-publication-3bbf: source compilation and publication
9. ctawiah/sync-source-planner-3bbf: planner integration
10. ctawiah/sync-descriptor-detach-3bbf: descriptor detach
11. ctawiah/sync-link-preparation-3bbf: link preparation
12. ctawiah/sync-link-command-3bbf: link commands
13. ctawiah/sync-reference-cleanup-3bbf: Phase 1 cleanup