refactor(twap_oracle): match instruction function order to Instruction enum

`idl-gen` emits IDL instructions in source order, and `spel` uses each
instruction's IDL position as its serde variant index. When the
`#[instruction]` function order diverges from the `twap_oracle_core::Instruction`
enum order, spel addresses the wrong instruction.

Move `update_current_tick` ahead of the TWAP-computation instruction so the
function order in twap_oracle.rs lines up with the enum variant order, and
regenerate artifacts/twap_oracle-idl.json to match.

No behavioral change — the instruction bodies are unchanged, only reordered.

artifacts/twap_oracle-idl.json

@@ -105,6 +105,35 @@
         }
       ]
     },
+    {
+      "name": "update_current_tick",
+      "accounts": [
+        {
+          "name": "current_tick_account",
+          "writable": true,
+          "signer": false,
+          "init": false
+        },
+        {
+          "name": "price_source",
+          "writable": false,
+          "signer": true,
+          "init": false
+        },
+        {
+          "name": "clock",
+          "writable": false,
+          "signer": false,
+          "init": false
+        }
+      ],
+      "args": [
+        {
+          "name": "price",
+          "type": "u128"
+        }
+      ]
+    },
     {
       "name": "publish_price",
       "accounts": [
@@ -176,35 +205,6 @@
           "type": "u64"
         }
       ]
-    },
-    {
-      "name": "update_current_tick",
-      "accounts": [
-        {
-          "name": "current_tick_account",
-          "writable": true,
-          "signer": false,
-          "init": false
-        },
-        {
-          "name": "price_source",
-          "writable": false,
-          "signer": true,
-          "init": false
-        },
-        {
-          "name": "clock",
-          "writable": false,
-          "signer": false,
-          "init": false
-        }
-      ],
-      "args": [
-        {
-          "name": "price",
-          "type": "u128"
-        }
-      ]
     }
   ],
   "accounts": [