feat(amm): expose supported fee tiers via feeTiers() op

The liquidity form's fee-tier selector was fed from the module's
newPositionContext, which hardcoded an empty list — leaving the selector
blank. Source the tiers from the program instead so the UI can never
drift from what the guest accepts.

Add amm_core::SUPPORTED_FEE_TIERS: the canonical ascending list of raw
bps ([1, 5, 30, 100]), built from the existing FEE_TIER_BPS_* constants.
is_supported_fee_tier's match is left unchanged and the new const is
unused on-chain, so the guest ImageID is unaffected; a drift-guard test
locks the list to the check (every entry accepted, neighbours rejected,
ascending/deduped).

Wire it through the stack:
- FFI: amm_fee_tiers op reading SUPPORTED_FEE_TIERS -> { feeTiers: [...] }
  (empty FeeTiersRequest, cbindgen header regenerated).
- Module: LogosList feeTiers() unwrapping the list, like tokenHoldings.
- Backend: QVariantList feeTiers() QtRO slot forwarding to the module.
- QML: LiquidityPage fetches backend.feeTiers() once (wallet-independent)
  and injects it into NewPositionForm, which wraps each int into a
  { feeBps } row for the existing delegate. Drop the now-dead feeTiers
  key from the flow's loadingContext().

apps/amm/qml/components/liquidity/NewPositionForm.qml

@@ -67,8 +67,13 @@ AmmActionCard {
     })
     readonly property var tokens: root.newPositionContext && root.newPositionContext.tokens
                                          ? root.newPositionContext.tokens : []
-    readonly property var feeTiers: root.newPositionContext && root.newPositionContext.feeTiers
-                                           ? root.newPositionContext.feeTiers : []
+    // Supported fee tiers as raw bps, injected from backend.feeTiers() (amm_core's
+    // SUPPORTED_FEE_TIERS). The selector's delegate wants { feeBps } rows, so wrap
+    // each int; labels are derived locally via feeLabel().
+    property var feeTiers: []
+    readonly property var feeTierModel: (root.feeTiers || []).map(function(bps) {
+        return { "feeBps": Number(bps) }
+    })
     readonly property var tokenA: root.tokenById(root.selectedTokenAId)
     readonly property var tokenB: root.tokenById(root.selectedTokenBId)
     readonly property int decimalsA: 0
@@ -407,7 +412,7 @@ AmmActionCard {
                 rowSpacing: 8
 
                 Repeater {
-                    model: root.feeTiers
+                    model: root.feeTierModel
 
                     Item {
                         id: feeTierOption

apps/amm/qml/pages/LiquidityPage.qml

@@ -21,6 +21,11 @@ Item {
     // account selectors; refetched when the wallet opens.
     property var holdings: []
 
+    // The AMM's supported fee tiers (backend.feeTiers()) feeding the fee selector.
+    // Program-derived and wallet-independent, so it's fetched once when the backend
+    // becomes available.
+    property var feeTiers: []
+
     function refreshHoldings() {
         if (!root.backend || root.runtime === null)
             return
@@ -29,9 +34,17 @@ Item {
             function(err) { console.warn("tokenHoldings error:", err) })
     }
 
-onBackendChanged: root.refreshHoldings()
-    onRuntimeChanged: root.refreshHoldings()
-    Component.onCompleted: root.refreshHoldings()
+    function refreshFeeTiers() {
+        if (!root.backend || root.runtime === null || root.feeTiers.length > 0)
+            return
+        root.runtime.watch(root.backend.feeTiers(),
+            function(list) { root.feeTiers = list },
+            function(err) { console.warn("feeTiers error:", err) })
+    }
+
+onBackendChanged: { root.refreshHoldings(); root.refreshFeeTiers() }
+    onRuntimeChanged: { root.refreshHoldings(); root.refreshFeeTiers() }
+    Component.onCompleted: { root.refreshHoldings(); root.refreshFeeTiers() }
 
     Connections {
         target: root.backend
@@ -237,6 +250,7 @@ onBackendChanged: root.refreshHoldings()
                                    : qsTr("Choose two tokens and a fee tier for this position.")
                     showRefreshAction: false
                     holdings: root.holdings
+                    feeTiers: root.feeTiers
                     newPositionContext: newPositionFlow.newPositionContext
                     flowState: newPositionFlow.viewState
 

apps/amm/qml/state/NewPositionFlow.qml

@@ -466,8 +466,7 @@ QtObject {
     function loadingContext() {
         return {
             "status": "loading",
-            "tokens": [],
-            "feeTiers": []
+            "tokens": []
         }
     }
 

apps/amm/src/AmmUiBackend.cpp

@@ -315,6 +315,14 @@ QVariantList AmmUiBackend::poolList()
     return readPoolsConfig();
 }
 
+QVariantList AmmUiBackend::feeTiers()
+{
+    // Pure, input-free enumeration of the AMM's supported fee tiers (raw bps) —
+    // no wallet or module connection state involved.
+    return m_logos->amm_module.feeTiers();
+}
+
+
 QVariantMap AmmUiBackend::createPool(QVariantMap request)
 {
     // Same connected-state submit guard as the swaps — this app's lock is

apps/amm/src/AmmUiBackend.h

@@ -85,6 +85,8 @@ public slots:
     // Reads the known-pools list from AMM_POOLS_CONFIG (app config JSON, read
     // here rather than in the amm_module — pool discovery is an app detail).
     QVariantList poolList() override;
+    // The AMM's supported fee tiers (raw bps) for the fee selector.
+    QVariantList feeTiers() override;
 
 private:
     void syncWalletState();

apps/amm/src/AmmUiBackend.rep

@@ -144,4 +144,10 @@ class AmmUiBackend
     // list if AMM_POOLS_CONFIG is unset/unreadable/invalid. This is app config, not
     // an on-chain read, so it lives in the backend rather than the amm_module.
     SLOT(QVariantList poolList())
+
+    // The AMM's supported fee tiers as raw basis points, ascending: [1, 5, 30,
+    // 100]. Input-free — sourced from amm_core's SUPPORTED_FEE_TIERS (the set the
+    // guest enforces), so the fee selector never hardcodes or drifts. The QML
+    // formats labels and decides selectability.
+    SLOT(QVariantList feeTiers())
 }