docs(website): theming & nav phases 0-2 as built

Matches RunicGateway/website's phases 0-2 of THEMING_AND_NAV.md.

BACKEND_DESIGN.md:
- The new /settings router group and its one route, plus why it is a fifth
  group rather than a route on an existing one.
- DELETE /admin/settings/:key in the admin route table, with the allowlist and
  why reset deletes instead of writing.
- The five unseeded theming/nav keys under the settings schema: absence of the
  row is the "use the default" state, values are TEXT so consumers parse, and
  malformed reads as absent.
- Route count 215 -> 225.

THEMING_AND_NAV.md:
- Phases 0-2 marked landed, with an "as landed" section recording the three
  things the design left open: where /settings/nav lives, where
  parseJsonSetting lives, and the exact 23-declaration radius promotion.
- The nav merge util's ordering rules, settled by the implementation: an
  untouched item keeps its index as its sort key, an explicit order wins a tie
  against a coincidental index, equal explicit orders keep code order, and
  `group` is honored only when it names an existing section.
- All four PR pairs target `edge`; the feature reaches `main` as one merge.

api-route-inventory.json: resynced from server/routes.manifest.json. Picks up
the two new routes plus eight that were already missing from the mirror since
the Protocol 3.0 cutover (shard clilocs, market, points).

Co-Authored-By: Claude <noreply@anthropic.com>

website/api-route-inventory.json

@@ -249,6 +249,10 @@
       "method": "PUT",
       "path": "/api/v1/admin/settings"
     },
+    {
+      "method": "DELETE",
+      "path": "/api/v1/admin/settings/:key"
+    },
     {
       "method": "POST",
       "path": "/api/v1/admin/shard/account"
@@ -293,6 +297,18 @@
       "method": "GET",
       "path": "/api/v1/admin/shard/char/:serial"
     },
+    {
+      "method": "GET",
+      "path": "/api/v1/admin/shard/clilocs"
+    },
+    {
+      "method": "POST",
+      "path": "/api/v1/admin/shard/clilocs/import"
+    },
+    {
+      "method": "PUT",
+      "path": "/api/v1/admin/shard/clilocs/path"
+    },
     {
       "method": "GET",
       "path": "/api/v1/admin/shard/houses"
@@ -817,10 +833,30 @@
       "method": "GET",
       "path": "/api/v1/public/shard/idoc"
     },
+    {
+      "method": "GET",
+      "path": "/api/v1/public/shard/market"
+    },
+    {
+      "method": "GET",
+      "path": "/api/v1/public/shard/market/meta"
+    },
+    {
+      "method": "GET",
+      "path": "/api/v1/public/shard/market/vendors/:serial"
+    },
     {
       "method": "GET",
       "path": "/api/v1/public/shard/online"
     },
+    {
+      "method": "GET",
+      "path": "/api/v1/public/shard/points"
+    },
+    {
+      "method": "GET",
+      "path": "/api/v1/public/shard/points/:system"
+    },
     {
       "method": "GET",
       "path": "/api/v1/public/shard/presence"
@@ -860,6 +896,10 @@
     {
       "method": "GET",
       "path": "/api/v1/public/wiki/tags"
+    },
+    {
+      "method": "GET",
+      "path": "/api/v1/settings/nav"
     }
   ],
   "internal": [