Port the fishing rods and wild Magikarp

The Old, Good and Super Rods run FishFunction facing water: the map's fish
group and Fish pick no fish, no bite, or a Pokémon from FishGroups and the
time of day's TimeFishGroups. The player casts and jiggles with the
fishing frames drawn from LoadFishingGFX's tiles, shows "!" on a bite, and
the hooked Pokémon attacks as BATTLETYPE_FISH. Facing pieces now use
signed offsets, which the rod above and left of the player needs.

Wild Magikarp no longer stop a battle: LoadEnemyMon redraws their DVs
through CalcMagikarpLength and its filters, as the original does. The
length routine matches the original in the reference emulator.

Part of #27

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/foundation-fixture.ts

@@ -12,7 +12,8 @@ import { generatePartyMon } from "../src/game/party/pokemon";
  * the Storm Badge, and New Bark Town and Cherrygrove City visited.
  * "headbutt" faces Route 29's first reachable Headbutt tree from below
  * with a Pokémon that knows Headbutt; Random always returning 0 drops a
- * sleeping Hoothoot. */
+ * sleeping Hoothoot. "fishing" faces the sea on New Bark Town's shore
+ * with the Old Rod, which then hooks a Magikarp. */
 export function foundationFixture(
   assets: CrystalAssets,
   room:
@@ -23,7 +24,8 @@ export function foundationFixture(
     | "pokegear"
     | "mom"
     | "fly"
-    | "headbutt",
+    | "headbutt"
+    | "fishing",
 ) {
   const world = new GameWorld(
     assets,
@@ -45,7 +47,8 @@ export function foundationFixture(
       }),
     );
     world.state.bag.items = [{ item: 18, quantity: 5 }]; // POTION
-    if (room === "candy") world.state.bag.items.push({ item: 0x20, quantity: 1 });
+    if (room === "candy")
+      world.state.bag.items.push({ item: 0x20, quantity: 1 });
   }
   if (room === "pokegear" || room === "mom") {
     world.state.party = [
@@ -80,10 +83,26 @@ export function foundationFixture(
     mon.pp = [15, 0, 0, 0];
     world.state.party = [mon];
     world.state.flags.add(OW.ENGINE_STORMBADGE);
-    for (const spawn of [14, 15]) // SPAWN_NEW_BARK, SPAWN_CHERRYGROVE
+    for (const spawn of [14, 15])
+      // SPAWN_NEW_BARK, SPAWN_CHERRYGROVE
       world.state.flags.add(assets.spawnEngineFlag(spawn)!);
     for (let event = 0; event < 8; event++) world.state.events.delete(event);
   }
+  if (room === "fishing") {
+    world.state.party = [
+      generatePartyMon(assets.pokemon, {
+        species: 155,
+        level: 8,
+        item: 0,
+        otId: world.playerId,
+        ot: "CHRIS",
+        dvs: 0x9abc,
+        caughtData: 0,
+      }),
+    ];
+    world.state.bag.keyItems.push(0x3a); // OLD_ROD
+    for (let event = 0; event < 8; event++) world.state.events.delete(event);
+  }
   if (room === "headbutt") {
     const mon = generatePartyMon(assets.pokemon, {
       species: 158, // TOTODILE
@@ -111,21 +130,26 @@ export function foundationFixture(
   const [map, x, y] =
     room === "headbutt"
       ? headbuttSpot(assets)
-      : room === "center" || room === "candy"
-        ? ["26:5", 9, 2]
-        : room === "poster"
-          ? ["24:7", 6, 1]
-          : room === "mom"
-            ? ["24:6", 7, 3]
-            : room && room !== "pokegear" && room !== "fly"
-              ? ["24:7", 2, 2]
-              : ["24:4", 9, 6];
+      : room === "fishing"
+        ? ["24:4", 17, 7]
+        : room === "center" || room === "candy"
+          ? ["26:5", 9, 2]
+          : room === "poster"
+            ? ["24:7", 6, 1]
+            : room === "mom"
+              ? ["24:6", 7, 3]
+              : room &&
+                  room !== "pokegear" &&
+                  room !== "fly" &&
+                  room !== "fishing"
+                ? ["24:7", 2, 2]
+                : ["24:4", 9, 6];
   world.restore({
     ...save,
     map,
     x,
     y,
-    direction: room === "mom" ? "down" : "up",
+    direction: room === "mom" ? "down" : room === "fishing" ? "right" : "up",
     objects: [],
   });
   return world;