Consolidate install-state.json manipulation with InstallStateManager

Background

PR microsoft/amplifier-app-cli#68 introduced surgical module dependency invalidation after self-updates. This required direct manipulation of install-state.json in two places:

• amplifier_app_cli/utils/update_executor.py - Invalidates modules with missing deps after update
• amplifier_app_cli/commands/reset.py - Clears install state when cache is removed

Current State

Both files now use a shared get_install_state_path() function from paths.py, but still manipulate the JSON file directly rather than using the InstallStateManager class from amplifier-foundation.

Implementation Plan

We chose Option A: Add methods to InstallStateManager in amplifier-foundation, then update amplifier-app-cli to use the new API.

Sub-Issues

• #194 - [foundation] Add consolidation API to InstallStateManager
• #195 - [app-cli] Use InstallStateManager API instead of direct JSON manipulation

Dependency Order

1. First: Merge #194 (foundation API)
2. Then: Merge #195 (app-cli migration)

Files Involved

• amplifier-foundation: amplifier_foundation/modules/install_state.py
• amplifier-app-cli: amplifier_app_cli/utils/update_executor.py
• amplifier-app-cli: amplifier_app_cli/commands/reset.py
• amplifier-app-cli: amplifier_app_cli/paths.py

Context

This was flagged during code review by @robotdad as a nice-to-have improvement for future consolidation.

Related PR: https://github.com/microsoft/amplifier-app-cli/pull/68

Start with amplifier_foundation/modules/install_state.py to understand the API added by sub-issue #194, then inspect direct install-state.json handling in amplifier_app_cli/utils/update_executor.py and amplifier_app_cli/commands/reset.py. Review amplifier_app_cli/paths.py for the shared path helper. Done means both app-cli locations use InstallStateManager rather than manipulating JSON directly, while preserving invalidation and reset behavior.