feat(amm): create TWAP price observations on behalf of the pool

Add a `CreatePriceObservations` instruction that registers a TWAP
price-observations account for a pool over a time window, via a chained
call to the configured TWAP oracle program. The pool acts as the price
source: the AMM authorizes it with its pool PDA seed so the oracle ties
the feed to that pool.

The feed's initial tick is read from the pool's authoritative
`CurrentTickAccount` (validated against its pool-derived PDA) rather than
being supplied by the caller, so the feed cannot be seeded at a forged
price — mirroring what `RecordTick` does. The clock is verified to be the
canonical 1-block LEZ clock, and creation is rejected if the observations
account already exists.

To support the chained call, `AmmConfig` and the `Initialize` instruction
are extended with a `twap_oracle_program_id` that the instruction reads.

artifacts/amm-idl.json

@@ -17,6 +17,10 @@
           "name": "token_program_id",
           "type": "program_id"
         },
+        {
+          "name": "twap_oracle_program_id",
+          "type": "program_id"
+        },
         {
           "name": "authority",
           "type": "account_id"
@@ -46,6 +50,12 @@
             "option": "program_id"
           }
         },
+        {
+          "name": "twap_oracle_program_id",
+          "type": {
+            "option": "program_id"
+          }
+        },
         {
           "name": "new_authority",
           "type": {
@@ -54,6 +64,47 @@
         }
       ]
     },
+    {
+      "name": "create_price_observations",
+      "accounts": [
+        {
+          "name": "config",
+          "writable": false,
+          "signer": false,
+          "init": false
+        },
+        {
+          "name": "pool",
+          "writable": false,
+          "signer": false,
+          "init": false
+        },
+        {
+          "name": "current_tick_account",
+          "writable": false,
+          "signer": false,
+          "init": false
+        },
+        {
+          "name": "price_observations",
+          "writable": false,
+          "signer": false,
+          "init": false
+        },
+        {
+          "name": "clock",
+          "writable": false,
+          "signer": false,
+          "init": false
+        }
+      ],
+      "args": [
+        {
+          "name": "window_duration",
+          "type": "u64"
+        }
+      ]
+    },
     {
       "name": "new_definition",
       "accounts": [
@@ -470,6 +521,10 @@
             "name": "token_program_id",
             "type": "program_id"
           },
+          {
+            "name": "twap_oracle_program_id",
+            "type": "program_id"
+          },
           {
             "name": "authority",
             "type": "account_id"