Fix Pi approval UI duplication and remove public debug slash commands

[mmprotest]

Motivation

• Remove duplicated approval text shown in both the widget and confirm dialog and make the confirmation dialog the single visible approval UX.
• Make approval dialog bodies concise and readable for common cases (Read/Bash/Write/Patch) without repeating titles or rendering [object Object].
• Hide public debug/test slash commands so only the intended /villani command is exposed while keeping internal helpers intact.

Description

• Change approval rendering so the approval widget is cleared before opening the confirm dialog and only a short approval status is set during confirmation, with the widget cleared again after confirmation (changes in integrations/pi-villani/src/index.ts).
• Simplify approvalMessage so the confirm body contains only operation-specific details (Command: / File: / Operation:) and ends with Approve this Villani action?, avoiding title repetition and [object Object] output (changes in integrations/pi-villani/src/index.ts).
• Update passive render handling so approval_required clears any widget and sets a brief approval status, and approval_resolved sets short accepted/denied continuation copy (changes in integrations/pi-villani/src/render.ts).
• Remove public registration of debug/test slash commands (/villani-abort, /villani-confirm-test, /villani-ping, /villani-doctor, /villani-bridge-ping, /villani-proxy-test) so only /villani is registered (changes in integrations/pi-villani/src/index.ts).
• Update tests and README to reflect the new behavior and public command list (changes in integrations/pi-villani/src/*.test.ts and integrations/pi-villani/README.md).
• Preserve internal helper functions and abort internals so core runner, model proxy behavior, bridge semantics, and shell/tool execution are unaffected (no changes outside Pi UI/command registration).

Testing

• Ran the package test suite with cd integrations/pi-villani && npm test, and all integration/unit tests passed (91 tests passed, 0 failed).
• Existing automated tests were updated to assert only /villani is registered publicly and to validate the approval lifecycle: widget cleared before confirm, concise status text, non-repetitive titles/bodies for Read/Bash/Write/Patch, no Pending approval or Allow this operation?, no [object Object], and that accepted/denied both clear the widget.

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Codex Task