[Epic] Make Azure assistance native and consistent across supported Copilot hosts

## Problem statement

Supported Copilot hosts differ in workspace, terminal, hooks, actions, rendering, localization, and packaging capabilities. Unmanaged differences create duplicated implementations and inconsistent Azure behavior.

## Outcome

Azure assistance follows shared product behavior while using each supported host's native capabilities intentionally.

## Goals

- Define supported hosts and capability contracts
- Keep terminology, safety, routing, and Azure tool behavior consistent
- Use native workspace, terminal, action, and rendering affordances
- Isolate host-specific adapters from shared skills

## Non-goals

- Forcing parity where host capabilities differ
- Supporting hosts without product ownership

## Success criteria

- [ ] Shared scenarios meet common behavior and safety expectations
- [ ] Intentional host differences are documented
- [ ] Compatibility tests cover supported integration surfaces

## Dependencies

Copilot client teams, plugin contracts, host test surfaces, and shared evaluation scenarios.

No files, tests, or entry points are named, so begin by locating the supported host integrations, plugin contracts, and host test surfaces referenced in the issue. Done means shared scenarios meet common behavior and safety expectations, intentional host differences are documented, and compatibility tests cover the supported integration surfaces.

Written by the indexing model from the issue text.