[Improve] Default /tasks filter to any user for admins

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Discord.

Related issue

Internal request from Discord (no tracked issue).

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Admins opening /tasks without an explicit user filter now default to Any User instead of themselves. Members still default to their own tasks. Autonomous categories continue to default to any user for everyone.

Why this change was made

Admins typically need a deployment-wide task view. Defaulting the filter to the current user forced an extra click every time they opened /tasks.

Impact

• Admins: /tasks lands on Any User with no userId query param
• Non-admin members: unchanged (still default to own tasks)
• Explicit userId (or choosing You / another user) still works as before

How it was tested

• pnpm --filter @roomote/web check-types
• Manual browser proof: signed in as admin via dev-login, opened /tasks with no query params, confirmed user filter shows Any User

Screenshots

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

No code issues found. See task

_{Reviewed 88156ee}