[Epic] LR-8 · Extensibility & Widget Sandboxing

[Deniel9204]

Make extensibility safe and powerful: sandbox widgets, add a discoverable bot/command framework, and ship new room types (forum, file-manager).

Why it's long-running: Widgets currently run unsandboxed with full app/system access and no crash isolation; there is no discoverable bot/command framework. Safe extensibility plus new room types is a security + architecture effort.

Tracked issues

• Add forum-style channel room type (MSC3765) #16 — Add forum-style channel room type (MSC3765)
• Sandbox matrix widgets #79 — Sandbox matrix widgets
• Bot/integration & discoverable command framework #80 — Bot/integration & discoverable command framework
• File-manager room type / widget #83 — File-manager room type / widget
• Capability-scoped widget sandboxing + resource limits + crash isolation
• Composer slash-command autocomplete/help

Related (tracked under other epics)

• Calendar: configurable week-start + timezone conversion #77 — Calendar: configurable week-start + timezone conversion
• User presence: null-check crash + status-message edit UI #78 — User presence: null-check crash + status-message edit UI
• Finish donation awards & activities #81 — Finish donation awards & activities
• Hover to see who reacted (desktop) #82 — Hover to see who reacted (desktop)

_{Epic LR-8 · area: extensions · auto-generated from ROADMAP.md §5.}