fix(sftp): keep browse sessions when switching side-panel tools

[netcatty-bot]

Summary

• Terminal side-panel SFTP no longer soft-closes (parks) browse channels when you switch to History / System / other tools while the panel chrome stays open.
• Directory listing cache and live SFTP sessions stay put, so switching back to File Transfer does not force reconnect + full reload.
• Closing the side panel still parks browse sessions (FileZilla-style), unless an editor tab or external-edit temp still needs the channel.
• Added lifecycle unit coverage for “panel open on another tool” vs “panel closed” park decisions, plus wiring assertions in the side-panel slot contract test.

Why

Opening File Transfer, then Logs (or another side-panel tool), then switching back remounted the list slowly and sometimes left a blank list. The owner React tree was already kept mounted across tool switches, but isVisible=false was treated as “non-interactive,” which parked browse SFTP sessions and cleared the listing cache. Restore then had to reconnect and re-list — expensive, and race-prone.

Changes

• isBrowseSessionInteractive gains ownerPanelOpen: keep browse warm while the terminal side panel is still open for that tab.
• SidePanelSftpSlot passes ownerPanelOpen={sidePanelOpenTabs.has(tabId)} into SftpSidePanel.
• Comments on main SftpView / useSftpState updated so parking is described as panel-close behavior, not every hide of the SFTP tool surface.

Testing

• node --test --import tsx application/state/sftp/browseSessionLifecycle.test.ts
• node --test --import tsx components/terminalLayer/sftpPanelLifecycle.test.ts
• node --test --import tsx application/state/editorTabSave.test.ts (promoted-editor retain path still green)
• Manual (unverified here): connect → open File Transfer → open Logs / System → switch back; list should appear immediately without reconnect. Close the side panel with no transfers and confirm browse still parks.

Fixes #2882

Automation

• Automated implement pass
• Review gate: @codex review (own/bot PRs only)
• Draft until Codex reports clean findings

[binaricat]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Bravo.

Reviewed commit: ac3993b789

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[netcatty-bot]

Codex reported no major issues. This PR is marked ready for human review/merge.

[chatgpt-codex-connector]

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Reviewed commit: ac3993b789

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[chatgpt-codex-connector]

Keep parked SFTP closed when reopening other tools

When an SFTP side panel was closed but kept mounted because a transfer or external edit was still active, the browse sessions either park after the activity finishes or should stay parked while the SFTP UI remains closed. With ownerPanelOpen driven by openTabs.has(tabId), opening History/System for that tab flips the hidden SFTP owner back to interactive even though SFTP is not visible, so useSftpState skips parking after the retained work completes (or restores already-parked browse sessions). This defeats the close-panel lifecycle and can keep/reopen SSH/SFTP browse connections just because a different side-panel tool is open; this should be gated on an actual SFTP tool switch from an open panel rather than any open side-panel tab.

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