Directional nodes: map Rotate updates direction / camera:direction

[tordans]

Problem

Mappers who tag standalone POIs with a technical bearing (direction=* or camera:direction=* in degrees, cardinals, or ranges—see OsmNode+Direction.swift) can preview the aim on the map as a direction wedge, but adjusting it today means opening the POI editor and using the compass flow (DirectionViewController via PresetValueTextField).

Area rotation is already map-native: choose Rotate, use the cyan arc overlay and rotation gesture, and geometry updates in place. Nodes without a selected parent way only get Duplicate; Rotate on a node inside a way still rotates the whole way. Standalone nodes with a direction tag had no equivalent “aim on the map” workflow.

Goal: For a standalone selected node whose direction or camera:direction value OsmNode.direction can parse, show Rotate in the edit menu and enter the same rotation overlay/gesture as areas—but write the tag (bearing in degrees, same convention as compass capture and the map wedge) instead of moving the node. Complements DirectionViewController; does not replace it.

Out of scope (this PR): Nodes that only infer direction from highway forward/backward on a way; nodes that are members of a way (way rotation unchanged).

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Implementation notes (by Cursor)

When Rotate appears

• In EditorMapLayer.editActionsAvailable(), standalone nodes (selectedNode only) append .ROTATE when technicalDirectionTagKey != nil.
• technicalDirectionTagKey is added on OsmNode and only matches direction / camera:direction values that directionFromString can parse (so direction=forward on a highway=stop node does not qualify).

Direction-edit rotate mode

• MapView.startObjectRotation() detects standalone + technical direction and calls EditorMapLayer.rotateDirectionBegin() (undo grouping + stored initial bearing/tag key).
• Same cyan rotation overlay and UIRotationGestureRecognizer as geometry rotation.
• rotateDirectionContinue(delta:) applies total gesture rotation to the initial bearing, writes degrees via mapData.setTags, calls setNeedsLayout() and didUpdateObject() for live wedge preview.
• Tag key preserved: existing direction vs camera:direction; numeric output like compass UI (MeasureDirectionViewModel). Arc spans (90-120) keep their width when rotated.
• endObjectRotation() finishes direction undo via rotateDirectionFinish().
• Direction-rotate session state (directionRotateTagKey, directionRotateInitialBearing) lives on the main EditorMapLayer class—not in the +Edit extension (Swift disallows stored properties in extensions).

Fallback behavior

• No parsable direction tag: Rotate is not listed for standalone nodes (same as today). Choosing Rotate on an in-way node without a standalone direction context still requires a way/multipolygon (unchanged error path).

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Testing notes (@tordans)

1. Build Go Map!! scheme on device or simulator (Linux CI cannot run Xcode here).
2. Unit tests: Run GoMapTests → OsmNode_DirectionTestCase (new cases for technicalDirectionTagKey, range formatting, highway forward exclusion).
3. Happy path
   • Select a standalone node with direction=90 or camera:direction=180 (e.g. bench, surveillance, viewpoint). – Only tested direction, camera:direction assumed to also work
   • Confirm Rotate appears in the edit toolbar / More sheet.
   • Tap Rotate → cyan arc overlay at node; two-finger rotate → wedge and tag value update live; release → undo group; tag is integer degrees.
4. Tag key
   • Node with only camera:direction → rotation updates that key, not direction.
5. Range (optional): direction=90-120 → after rotate, still a range with same angular width.
6. Regression
   • Closed way / multipolygon: Rotate still moves geometry.
   • Node in way (no standalone selection): Rotate still rotates way, not tag-only.
   • Standalone node without direction tag: no Rotate.
   • highway=stop + direction=forward: no Rotate on standalone (no technical direction). – Not tested (yet)
7. Sign / feel: Verify wedge rotation direction matches finger rotation; report if inverted (implementation uses negated gesture delta to align with geometry rotate).

Before	After
rotate-node--before.min.mov	rotate-node--after.min.mov

Ping openstreetmap/iD#12104 and especially openstreetmap/iD#12341 where this idea comes from.