Add session create control and remote host polish

[falkoro]

Summary

• add an explicit /api/create route for known tmux sessions and wire it to the selected-session action bar
• change stopped known sessions from Start wording to Create, including the safe-shot mock and docs
• add a real remote-host loading state with busy markers and first-load error fallback
• make compact remote container rows passive so only restart/pull buttons trigger actions

Verification

• bun run build:frontend
• bun run check
• rustfmt --edition 2021 --check src/routes.rs src/tmux.rs
• cargo test
• cargo build
• isolated /api/create smoke test with disposable tmux session sd-create-test
• Playwright desktop and narrow checks for Create, remote loading, and passive remote container rows

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.