Users, file manager, image generation, budgets and agent workflow

- User management: local accounts (Argon2) and OpenID Connect, admin/user
  roles, per-user folders plus admin-shared folders, read-only session
  sharing, event filtering per user
- File manager with CodeMirror editor and git client (status, diff,
  stage, commit, branches, fetch/pull/push, log, clone/init)
- Image generation via fal.ai: generate_image tool and image page
- Budgets: monthly limits per provider, provider balances/costs
  (OpenRouter, Anthropic admin cost report, fal.ai), price discovery
- Subagents on other models, background tasks, concurrency limits per
  host/model/subagent
- MCP tools loaded on demand (mcp_search/mcp_call), read-only hints
- Permission mode "auto", safe read-only commands always allowed
- Persistent message queue with attachments, deletable
- Live reasoning incl. <think> tags, activity animations, CSS themes,
  mobile layout, statistics per user, upload size handling
- Docker: named volume for state, localhost-bound port

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/tools/agent.rs

@@ -143,7 +143,8 @@ impl Tool for Task {
         "Launch a subagent to handle an independent, multi-step task in its own context (e.g. a \
          broad codebase search, a focused review). The subagent only knows what you put in the \
          prompt – write a complete, self-contained brief. Its final message is returned to you. \
-         Several task calls in one response run in parallel."
+         Several task calls in one response run in parallel (subject to the configured limits). \
+         With background=true you continue working and receive the result later."
             .into()
     }
     fn schema(&self) -> Value {
@@ -152,7 +153,8 @@ impl Tool for Task {
             "properties": {
                 "description": {"type": "string", "description": "Short (3-5 words) task description"},
                 "prompt": {"type": "string", "description": "The full brief for the subagent"},
-                "subagent_type": {"type": "string", "description": "Subagent to use (default: general)"}
+                "subagent_type": {"type": "string", "description": "Subagent to use (default: general)"},
+                "background": {"type": "boolean", "description": "Run in the background: returns immediately, the result arrives later as a message. Use for work you don't need right away (e.g. writing docs, summaries, translations)."}
             },
             "required": ["description", "prompt"]
         })