docs(claude): note cross-project funplay-* entries in generated CLAUDE.md guidance

[dehuaichendragonplus]

Summary

• Claude Code's connection health check surfaces every registered MCP server on the machine regardless of which project a session was opened in. Once two Funplay-enabled projects have each been configured under 0.6.3's project-scope fix, a session in one project still sees the other project's now-correctly-scoped entry reported as "Failed to connect" whenever that project's Editor isn't open — project-scoping fixed routing, not what a session's health check displays.
• This plugin has no way to prove another project's entry is safe to delete (it may be in active use by a project that simply isn't open right now), so there is nothing to fix in the scoping logic itself. This PR instead adds a note to the generated Claude Code guidance block (BuildClaudeManagedBlock in ProjectSkillsManager.cs) so an agent reading its project's CLAUDE.md checks whether a failing funplay-* entry's name matches the current project before concluding Funplay is broken.
• CHANGELOG.md gets a matching [Unreleased] entry.

Test plan

• Verified the diff is purely additive (2 files, 4 insertions, 0 deletions) against a freshly synced main.
• Recompiled in a Unity test project after the change; get_compilation_errors reported no errors.
• Regenerated CLAUDE.md via the Funplay panel and visually confirmed the new bullet renders correctly in the managed block.

🤖 Generated with Claude Code