[AZ-450] [AZ-451] [AZ-452] [AZ-454] Externalize URLs + accessors

Refactor batch 1 of 2 for the 01-testability-refactoring epic
(AZ-447). Minimal-surgical edits to make the UI's external
dependencies overridable for the test profiles in
_docs/02_document/tests/environment.md.

- AZ-450 (C03): tile URLs externalized to VITE_OSM_TILE_URL and
  VITE_ESRI_TILE_URL with the production strings as defaults.
  Fixes the AC-N3 / NFT-RES-03 air-gap regression and lets the
  e2e profile's tile-stub serve tiles deterministically.
- AZ-451 (C04): Leaflet marker icon imported from the pinned
  leaflet package as a Vite asset; removes the unpkg.com CDN
  reference (also fixes the leaflet@1.7.1 vs ^1.9.4 mismatch).
- AZ-452 (C05): getApiBase() accessor reading
  VITE_API_BASE_URL. request(), refreshToken(), and createSSE()
  prepend the prefix. Default '' preserves every call site.
- AZ-454 (C07): JSDoc on setToken/getToken documenting the
  test-override intent so future cleanup doesn't delete them.

Also: .env.example documents every VITE_* var; vite-env.d.ts
declares ImportMetaEnv; .gitignore now excludes /dist and
*.tsbuildinfo (tracked-by-mistake cache file removed).

Build verification: `bunx tsc -b --noEmit` passes. No tests in
this run (testability-run exemption per refactor SKILL — tests
land in autodev Step 6).

Co-authored-by: Cursor <cursoragent@cursor.com>

src/features/flights/mapIcons.ts

@@ -1,4 +1,5 @@
 import L from 'leaflet'
+import markerIcon from 'leaflet/dist/images/marker-icon.png'
 
 function pinIcon(color: string) {
   return L.divIcon({
@@ -15,7 +16,7 @@ export const pointIconBlue = pinIcon('#228be6')
 export const pointIconRed = pinIcon('#fa5252')
 
 export const defaultIcon = new L.Icon({
-  iconUrl: 'https://unpkg.com/leaflet@1.7.1/dist/images/marker-icon.png',
+  iconUrl: markerIcon,
   iconSize: [25, 41],
   iconAnchor: [12, 41],
   popupAnchor: [1, -34],

src/features/flights/types.ts

@@ -52,7 +52,13 @@ export const PURPOSES = [
 
 export const COORDINATE_PRECISION = 8
 
+const trimTrailingSlash = (s: string) => s.replace(/\/+$/, '')
+
 export const TILE_URLS = {
-  classic: 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
-  satellite: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
+  classic:
+    trimTrailingSlash(import.meta.env.VITE_OSM_TILE_URL ?? '') ||
+    'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
+  satellite:
+    trimTrailingSlash(import.meta.env.VITE_ESRI_TILE_URL ?? '') ||
+    'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
 } as const