feat(data): add content schema definitions

JSON Schema (draft 2020-12) for content validation: district,
location, npc-profile, dialogue-pool, monologue-pool, triangle,
routine, and fact-catalog. NPC schema uses if/then conditional
for FRIEND pattern validation. Implements ticket #386.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

content/_schema/location.schema.json

@@ -0,0 +1,54 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "location.schema.json",
+  "title": "Location Definition",
+  "description": "Location metadata — one file per location (D-025, D-036).",
+  "type": "object",
+  "required": ["canonical_id", "display_name"],
+  "additionalProperties": false,
+  "properties": {
+    "canonical_id": {
+      "type": "string",
+      "pattern": "^[a-z]+\\.[a-z]+\\.[a-z-]+\\.location\\.[a-z][a-z0-9-]*$",
+      "description": "Full canonical ID: {system}.{station}.{district}.location.{slug}"
+    },
+    "display_name": {
+      "type": "string",
+      "minLength": 1
+    },
+    "description": {
+      "type": "string"
+    },
+    "tile_bounds": {
+      "type": "object",
+      "description": "Rectangular tile bounds for this location",
+      "properties": {
+        "x_min": { "type": "integer" },
+        "y_min": { "type": "integer" },
+        "x_max": { "type": "integer" },
+        "y_max": { "type": "integer" },
+        "z": { "type": "integer" }
+      },
+      "required": ["x_min", "y_min", "x_max", "y_max", "z"]
+    },
+    "sightlines": {
+      "type": "object",
+      "description": "Sightline properties for LOS computation",
+      "properties": {
+        "open": {
+          "type": "boolean",
+          "description": "True if the location is open-plan (no internal walls)"
+        },
+        "notes": { "type": "string" }
+      }
+    },
+    "ambient_sound": {
+      "type": "string",
+      "description": "Reference to ambient sound asset"
+    },
+    "social_site": {
+      "type": "string",
+      "description": "Social site template this location belongs to"
+    }
+  }
+}