feat: Ticket 4.2 Pyth Oracle Integration (on-chain) (#66)

- Dynamic Pyth V2 price offset (48 + num x 96) - works on real feeds
- Optional oracle in MatchOrdersAccounts - backward-compatible
- Oracle price + timestamp cached to Market account
- PMM effective price with clamped inventory skew [-100%%, +100%%]
- 3 integration tests + 9 unit tests for oracle validation
- Zero new crate deps, zero [patch] sections, zero clippy warnings

Author: 0xfave

src/instruction.rs

@@ -305,15 +305,22 @@ pub struct MatchOrdersAccounts<'a> {
     pub quote_vault: &'a AccountView,
     pub buyer_order: &'a AccountView,
     pub seller_order: &'a AccountView,
+    pub oracle_price: Option<&'a AccountView>,
 }
 
 impl<'a> TryFrom<&'a [AccountView]> for MatchOrdersAccounts<'a> {
     type Error = FluxDexError;
 
     fn try_from(accounts: &'a [AccountView]) -> Result<Self, Self::Error> {
-        if accounts.len() != 7 {
-            return Err(FluxDexError::InvalidAccountCount);
-        }
+        // Accept 7 accounts (no oracle) or 8 accounts (with oracle).
+        let oracle_price = if accounts.len() == 8 {
+            Some(&accounts[7])
+        } else {
+            if accounts.len() != 7 {
+                return Err(FluxDexError::InvalidAccountCount);
+            }
+            None
+        };
 
         let [
             crank_authority,
@@ -323,7 +330,7 @@ impl<'a> TryFrom<&'a [AccountView]> for MatchOrdersAccounts<'a> {
             quote_vault,
             buyer_order,
             seller_order,
-        ] = accounts
+        ] = &accounts[..7]
         else {
             return Err(FluxDexError::InvalidArgument);
         };
@@ -362,6 +369,7 @@ impl<'a> TryFrom<&'a [AccountView]> for MatchOrdersAccounts<'a> {
             quote_vault,
             buyer_order,
             seller_order,
+            oracle_price,
         })
     }
 }

src/lib.rs

@@ -5,6 +5,7 @@ use pinocchio::{AccountView, Address, ProgramResult, entrypoint};
 pub mod error;
 pub mod instruction;
 pub mod magicblock;
+pub mod oracle;
 pub mod pmm;
 pub mod processor;
 pub mod state;