feat(tab): add session lock and SecureCRT-style connection status badges

[aries-shen]

• Session lock: password prompt (kept in memory, SHA-256 hashed), lock/unlock via tab context menu, 'Lock All Sessions' / 'Hide Output' options, and input gating so locked terminals reject keystrokes until unlocked.
• Connection status badges (SecureCRT-inspired): connected = plain green check, disconnected = red circle with white bar, connected+locked = combined green check with yellow lock overlay at bottom-right. Rendered after the tab type icon with tooltips for both regular and pinned tabs.
• Locked tabs cannot be closed via the X button; close_tab central guard blocks it and surfaces a notification prompting the user to unlock first.
• Terminal reports connection state (mapped from PTY/connection status, read-only surfaces show no badge) and emits StateChanged on transitions; SFTP uses a connection-state helper with the same transition semantics.

Closes #[issue number]

Description

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Please keep 1 PR to solve 1 problem, and keep Small improvements should be small modifications to make PR easier to review and to merge.

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Break Changes

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Checklist

• I have read the CONTRIBUTING document and followed the guidelines.
• Reviewed the changes in this PR and confirmed AI generated code (If any) is accurate.
• Passed cargo run for story tests related to the changes.
• Tested macOS, Windows and Linux platforms performance (if the change is platform-specific)

[feigeCode]

感谢贡献