galaxy(renderer): SVG system view with station markers

[ScottyVenable]

Owner: Sol
Parent: #91

Goal

Flesh out the SVG SystemMap so each star system reads as a distinct
on-screen object with legible station markers, kind icons, and inline
distance / risk labels.

Acceptance criteria

• Distinct angular SVG glyphs per StationKind (Trade Hub, Industrial,
  Agricultural, Research, Mining, Military, Frontier Outpost, Pleasure
  Resort, Refinery, Black Market). Glyphs share visual weight inside a
  12px bounding box.
• Station label, kind, and faction colour rendered next to each glyph.
• Distance from the player's current station and route risk shown when
  the system is the active travel target.
• Tap / click highlights a station and surfaces it as the selected
  destination via onSelectStation.
• 44px minimum hit area on touch viewports (transparent SVG hit-rect
  overlays where needed).
• No emoji, no Math.random.

Out of scope

Galaxy renderer pan/zoom (sub-task 1) and Helm / mini-map integration
(sub-task 3).

Branch suggestion

feat/sol-system-map-markers