feat: add custom route to invite user and automatically start DM

[ggurdin]

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Pull Request has been tested on:

• Android
• iOS
• Browser (Chromium based)
• Browser (Firefox based)
• Browser (WebKit based)
• Desktop Linux
• Desktop Windows
• Desktop macOS

[Copilot]

Pull request overview

Adds a custom deep link route (/invite_user/:userID) so users can share an invite URL that, when opened, automatically creates/opens a direct message with the inviter (including a logged-out flow via cached storage).

Changes:

• Update invite sharing to generate a deep link to /#/invite_user/<mxid>.
• Add UserInviteLink route + page to start a DM (or cache the mxid until login).
• Start a DM on app load when a cached invite user ID exists.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
lib/utils/fluffy_share.dart	Changes the shared invite text to a deep link that encodes the inviter’s mxid.
lib/pangea/user/user_invite_link_repo.dart	Adds GetStorage-backed persistence for an “invite user” mxid across login.
lib/pangea/user/user_invite_link_page.dart	Introduces the route handler page that triggers DM creation or caches the mxid when logged out.
lib/pages/chat_list/chat_list.dart	On first sync, reads cached invite mxid and creates/opens the DM.
lib/main.dart	Initializes the new GetStorage box (user_invite_storage).
lib/config/routes.dart	Registers the new GoRouter path /invite_user/:userID.

[Copilot]

When _startDM() fails, initState treats it the same as a null result and redirects to /home without surfacing the error to the user (and the widget builds an empty SizedBox, so the screen is blank while the request runs). Consider using showFutureLoadingDialog (as in ChatListController) or otherwise showing progress + an actionable error instead of silently bouncing to home.