Replace manual disconnect teardown with owner resets

[ctoth]

Summary

• add a reusable, ordered disconnect-reset lifecycle and automatically register GMCP/MCP package resets
• move session teardown from MudClient's manual feature roll-call to the feature owners while preserving history, input, preferences, editor state, and lifetime listeners
• clear local transport state on disconnect and reject commands unless a live local stream or OPEN WebSocket is connected

Root cause and impact

Disconnect cleanup had accumulated as a centralized list in MudClient, so new stateful packages could be added without joining the teardown path. That left session state behind across reconnects. The local transport path also retained stale references, and command sends could reach closed or missing transports after local echo had already been recorded.

This PR makes disconnect ownership explicit at package registration, preserves the file-transfer-before-GMCP cleanup ordering, and surfaces closed-transport command failures without false local echo.

Validation

• npm test — 104 files, 1,050 tests
• npm run typecheck
• staged Biome lint for each commit and precommit hook
• npm run build
• git diff --check origin/master..HEAD

Fixes #78
Fixes #60