fix: sky port behavior, default sky altitude, Sky Realm robustness, and unfly state restore

Summary

Ground burgs with sky ports keep land capabilities and land routes.
Only truly flying burgs join the Sky Realm; turning off “flying” restores the ground state.
Replace magic altitude 1000 with a DOM-configurable default.
Guard state hover/pin logic for geometry-less Sky Realm to prevent console errors.
Watabou link uses sky settings only for flying burgs.
Details

Land routing with sky ports:

Change: include sky ports in land road/trail networks; exclude only flying burgs.
Why: sky ports should not impose flying/land restrictions on a ground burg.
File: modules/routes-generator.js
Sky port toggle does not move state:

Change: toggling skyPort no longer assigns the burg’s state to the Sky Realm or reassigns cell ownership.
Why: sky port ≠ flying city; it’s just air connectivity.
File: modules/ui/burg-editor.js
Flying toggle and state restore:

Change: enabling “flying” assigns the burg to the Sky Realm but does not overwrite the cell’s ground state; disabling “flying” restores the burg’s state to the underlying ground state (pack.cells.state[burg.cell]).
Change: when relocating, assign Sky Realm only if the burg is placed over water; ground placements keep ground state.
Why: fixes bug where reverting to ground left burg in Sky Realm and preserves ground sovereignty.
File: modules/ui/burg-editor.js
Default sky altitude via DOM (no more magic 1000):

Change: add hidden input #burgDefaultSkyAltitude (default 1000 m) and read it everywhere altitude is defaulted (editor and “add burg on water” flow).
Why: centralizes default, documents units, and makes it configurable without touching code.
Files: index.html, modules/ui/burg-editor.js, modules/ui/burgs-overview.js
Sky State creation robustness:

Change: initialize a neutral diplomacy row for the new Sky State and extend existing states’ diplomacy arrays.
Change: do not forcibly set the anchor cell ownership to Sky state when creating the Sky Realm.
Why: prevents UI/editor crashes that assume diplomacy is rectangular; avoids accidental land transfer to Sky Realm.
File: modules/ui/editors.js
State hover/pin guards for Sky Realm:

Change: skip fog/hover/highlight when the target state has no geometry (e.g., Sky Realm) or the path is missing.
Why: fixes console errors in State hover and Pin feature.
Files: modules/dynamic/editors/states-editor.js, modules/ui/diplomacy-editor.js, modules/ui/military-overview.js
Watabou integration:

Change: only treat burgs as “sky” for city links when flying is true (not when only skyPort is set).
Why: ground burgs with sky ports should still have gates/roads/hubs/shanty, etc.
File: modules/ui/editors.js
User-visible Effects

Ground cities can have sea port + sky port + roads/trails simultaneously.
Toggling flying on shows altitude row; default altitude is read from the DOM.
Toggling flying off restores the burg to its ground state affiliation.
No more console errors when interacting with state hover/pin around the Sky Realm.
Potential Impacts

Land route generation may produce additional roads because sky-ported (but ground) burgs are now included.
Diplomacy arrays gain a neutral column for the Sky Realm when first created (non-breaking, UI-aligned).
Test Plan

Set sky port on a ground burg: verify roads/trails remain; sea port and other features unaffected.
Toggle flying on: burg state switches to Sky Realm; cell remains with ground state; altitude defaults from #burgDefaultSkyAltitude; air routes generate.
Toggle flying off: burg state returns to the ground state; altitude row hides; routes regenerate.
Hover/fog/pin states with the editors open: no errors with Sky Realm selected or hovered.
Open Watabou (city generator) links:
Ground + sky port: uses ground settings (gates/roads/hubs/shanty allowed).
Flying: uses sky settings (no farms/gates/hub etc. as appropriate).
Files Changed

modules/routes-generator.js
modules/ui/burg-editor.js
modules/ui/burgs-overview.js
modules/ui/editors.js
modules/dynamic/editors/states-editor.js
modules/ui/diplomacy-editor.js
modules/ui/military-overview.js
index.html

index.html

@@ -3413,6 +3413,8 @@
                 <div class="label">Altitude:</div>
                 <input id="burgAltitude" type="number" min="0" step="50" style="width: 9em" /> m
               </div>
+              <!-- Hidden default for sky altitude (meters) -->
+              <input id="burgDefaultSkyAltitude" type="number" value="1000" style="display: none" />
 
               <div data-tip="Burg average yearly temperature" style="display: flex; justify-content: space-between">
                 <div>