Dedupe Rust sidebars for tmux grouped sessions

[colelawrence]

Summary

• dedupe tmux active-window discovery by physical window id so grouped sessions do not spawn multiple Rust sidebars into the same shared window
• dedupe sidebar pane discovery/cleanup by physical pane id so linked-session listings do not look like duplicate panes
• add regression coverage for grouped-session toggle behavior

Verification

• cargo test -p opensessions-runtime --test tmux_provider
• cargo test -p opensessions-server --test protocol_shell http_toggle -- --nocapture

[inspect-review]

inspect review

Triage: 13 entities analyzed | 0 critical, 0 high, 8 medium, 5 low
Verdict: standard_review

Findings (1)

1. [low] Test/implementation mismatch in tmux_provider window dedupe: list_active_windows only replaces an existing entry when current.active==false && next.active==true, but the new test tmux_provider_deduplicates_grouped_session_windows_by_window_id expects the second @1 entry (alpha-2) to win even though the first @1 entry is already active. Diff evidence: implementation in packages/runtime-rs/src/tmux_provider.rs uses if !current.active && next.active { *current = next; } and the test data marks alpha-2 active (...alpha-2...1...) while alpha is also active per the test fixture; test asserts session_name == "alpha-2". This will fail if the first entry is active.

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Reviewed by inspect | Entity-level triage found 0 high-risk changes

[rs545837]

Thanks for the PR @colelawrence, will review it soon.