feat: per-map configurable start camera position (#427)

[Apezdr]

Summary

Closes #427

Extends the map config with five new optional fields that control the full initial camera state when a map is opened without a URL hash:

• start-distance — zoom/camera distance (default: 1500)
• start-rotation — horizontal camera rotation in radians (default: 0)
• start-angle — vertical camera angle in radians (default: 0)
• start-tilt — camera tilt in radians (default: 0)
• start-view — initial view mode: "perspective", "flat", or "free" (default: "perspective")

These complement the existing start-pos field. All five default to the same values as before, so existing configs are unaffected.

Example config

start-pos: { x: 118, z: -148 }
start-distance: 59
start-rotation: 2.86
start-angle: 1
start-view: "perspective"

The values map directly to the URL hash format (#mapId:x:y:z:distance:rotation:angle:tilt:ortho:state), making it easy to copy a position from the browser bar into the config.

Changes

• MapConfig — five new fields with safe defaults
• MapSettings — default interface getters for the new fields
• MapSettingsSerializer — emits all five fields into each map's settings.json
• map.conf template — documents the new options
• Map.js — parses the new fields from settings.json
• BlueMapApp.resetCamera() — applies per-map start values; start-view takes priority over the global defaultToFlatView setting, with graceful fallback when the requested view is not enabled on the map

Test plan

• Open map without URL hash — camera starts at configured position/distance/angle
• Existing maps with no new config use the same defaults as before (distance 1500, perspective view)
• start-view: "flat" opens in flat/isometric view
• start-view: "free" opens in free-flight view
• If start-view requests a disabled view, falls back to the next available view
• URL hash still overrides the config start position when present