[FEATURE]: /reload slash command with auto-resume

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Describe the enhancement you want to request

This is a follow-up to #6719 and the shelved PR #9871, with a working implementation on a fork.

Problem: Any change to config, agents, skills, MCP servers, or plugins requires a full restart of opencode. This interrupts running sessions and loses context.

Proposed solution: A /reload\ slash command that hot-reloads everything without restarting the TUI:

1. ConfigReload service — per-workspace state tracking with pending/executing/done lifecycle. Queues reload if sessions are active, executes when idle. Coalesces repeated requests during an active reload.
2. Auto-resume — after reload completes, the interrupted session is automatically resumed via \SessionPrompt.loop(). No synthetic continuation prompt; the loop reloads history from DB and continues with fresh config.
3. 
   eload_config\ tool — agent-callable tool that triggers reload and stops the current turn via \stopAfterToolResult. The agent can reload config mid-session and the session continues automatically.
4. Server endpoints: \POST /config/reload, \GET /config/reload/status, \POST /config/bootstrap-complete\ for TUI reconnection after instance reload.
5. Bootstrap cycle tracking — TUI acknowledges reload completion with a matching cycle number, preventing stale acks from dismissing the reload overlay prematurely.

Working implementation:
eload-command\ branch on https://github.com/AndyS77/opencode

Key differences from PR #9871:

• Auto-resume: the interrupted session is automatically resumed after reload (PR #9871 did not resume)
• Error handling: \store.reload()\ failures are logged instead of silently swallowed (\Effect.ignore\ → \Effect.catchCause)
• No dead code: removed \oid ConfigReload.Event\ and \s any\ casts
• Tests cover auto-resume path with mocked \SessionPrompt.Service\

What gets reloaded:

• Global + project config (\opencode.json/\ \opencode.jsonc)
• Agents, skills, commands (from .opencode/\ and config)
• MCP server connections (disconnect + reconnect)
• Plugin registry (full re-import)
• Provider configuration and auth
• LSP connections, file watchers, permissions, formatters

Related issues: #6719, #8751, #39987, #37426