fix: server icons survive a disk cleaner, and an allow list keeps Plug's search tool

[cyberpapiii]

What

Server icons, and the fixes from an audit of everything changed since 0.10.0.

• Icons. Found icons were kept in the system cache, which a disk cleaner empties. The search that refetched them at launch was cancelled when the server list settled, and the cancel was stored as "no icon" for a day. Found icons now sit beside the chosen ones, and a cancelled search stores nothing.
• Allow list. A client with an allow list keeps Plug's own search tool. Removing a server takes it off every allow list, and an emptied list still holds. A watch on a tool not listed right now is checked by server and tool.
• Sign-in. A replayed renewal token ends the sign-in in memory even when the save fails.
• Tasks. A task called by its server's own tool name records its server, so its large result is readable by the client that ran it.
• Cleanup. One duplicate access check removed, one client key built by the shared helper, one repeated session check named, and two process spawns skipped when their answer is not needed.

Checked

./scripts/dev.sh (all lanes), ./scripts/dev-install.sh, icons present after install.

🤖 Generated with Claude Code