Direct Selection tool: reshape pen and shape paths after they're drawn (#790) (#865)

* Direct Selection tool: reshape paths after they're drawn (#790)

Adds Photoshop's Direct Selection tool (A, in the Path Selection flyout) and
the Pen's Cmd/Ctrl (Direct Selection) and Alt (Convert Point) modifiers. It
selects and drags anchors, direction handles and segments of the work path,
the active shape layer's path and a targeted vector mask.

The geometry lives in photocraft_vector::edit; new engine commands
path.moveAnchors, path.moveHandle, path.bendSegment and path.convertPoint
apply it (one history step per drag, drivable over MCP and the control
channel), and the canvas previews a drag with the same code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Tool::ALL holds 49 tools now that Direct Selection and Magnetic Lasso both landed

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>

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