PMVP: Add Explorer create rename delete with safe confirmations

[webfish0]

Next MVP hardening item after the initial usable workbench slice.

Need:

• Create file from Explorer/minibuffer.
• Rename selected file/folder from Explorer/minibuffer.
• Delete selected file/folder only after explicit confirmation.
• Refresh Explorer after file operations.
• Preserve active editor/dirty state safely.

Acceptance:

• End-user scripted evidence covers create, rename, delete-cancel, delete-confirm, and refresh.
• Remote readback/listing proves operations occur on the SSH workspace.
• Full product MVP verification passes.

[webfish0]

Implemented in commit 986e74c (fix: remove unclear rail and harden mouse input).

Change:

• Added SSH-backed rename and delete operations.
• Added create file, rename active/selected file, delete confirmation/cancel flows through command palette/minibuffer.
• Quick Open now searches recursively instead of only visible Explorer rows.
• Evidence generation now renders named key-frame screenshots for create, rename, delete-cancel, delete-confirm, search, terminal, and minimum-size states.

Verification:

• npm run verify:product-mvp passed.
• MANUAL-MVP-001 covers create, rename, delete cancellation, confirmed delete, remote readback, and confirmed missing deleted file.
• Key screenshot evidence under test-evidence/manual-product-mvp/screenshots/frames/.

[webfish0]

Closing: implemented and verified in 986e74c.