Create operators from the C-x C-f picker

[edwin-zvs]

Summary

• add operator beside project in the C-x C-f creation picker
• open a focused unsaved operator editor with a collision-safe default name
• remove the /serve slash command and update operator docs/specification

Tests

• cargo test -p construct-cli harness_picker -- --nocapture
• cargo test -p construct-cli new_picker_operator_action_opens_a_unique_focused_draft_and_serve_is_removed -- --nocapture
• cargo test -p construct-cli: 1410 passed; the sole failure, color::tests::truecolor_backend_still_emits_rgb, reproduces on untouched main
• cargo build

[edwin-zvs]

Updated flow at 9b64ca8:

1. C-x C-f → operator
2. Enter the operator name in the minibuffer (Operator name:).
3. The focused unsaved operator editor opens under that name.

Picker

The new name prompt and resulting triage editor were verified in a deterministic TUI recording.

[edwin-zvs]

After: C-x C-f shows operator beside project, then choosing it opens the focused unsaved operator editor.

Picker

Operator editor