feat: scanner unknown value + comparison rescan modes, find bar height fix

Add Cheat Engine-style scan conditions: Unknown Value captures all
aligned addresses as baseline, then Changed/Unchanged/Increased/Decreased
narrow results by comparing current vs previous values. Exact Value
mode unchanged. Also fix find bar search box height to match buttons
and improve MCP bridge instructions.

src/scanner.h

@@ -10,26 +10,6 @@
 
 namespace rcx {
 
-// ── Scan request / result ──
-
-struct ScanRequest {
-    QByteArray pattern;             // literal bytes to match
-    QByteArray mask;                // 0xFF = must match, 0x00 = wildcard
-
-    bool filterExecutable = false;  // only scan +x regions
-    bool filterWritable   = false;  // only scan +w regions
-
-    int alignment  = 1;             // 1 = every byte, 4 = dword, 8 = qword
-    int maxResults = 50000;
-};
-
-struct ScanResult {
-    uint64_t   address;
-    QString    regionModule;
-    QByteArray scanValue;       // cached bytes at scan/update time
-    QByteArray previousValue;   // value before last update
-};
-
 // ── Value scan types ──
 
 enum class ValueType {
@@ -41,6 +21,40 @@ enum class ValueType {
     HexBytes
 };
 
+// ── Scan condition (Cheat Engine-style) ──
+
+enum class ScanCondition {
+    ExactValue,      // first scan + rescan: match specific bytes
+    UnknownValue,    // first scan only: capture all aligned addresses
+    Changed,         // rescan: current != previous
+    Unchanged,       // rescan: current == previous
+    Increased,       // rescan: current > previous (numeric)
+    Decreased        // rescan: current < previous (numeric)
+};
+
+// ── Scan request / result ──
+
+struct ScanRequest {
+    QByteArray pattern;             // literal bytes to match (empty for UnknownValue)
+    QByteArray mask;                // 0xFF = must match, 0x00 = wildcard
+
+    bool filterExecutable = false;  // only scan +x regions
+    bool filterWritable   = false;  // only scan +w regions
+
+    int alignment  = 1;             // 1 = every byte, 4 = dword, 8 = qword
+    int maxResults = 50000;
+
+    ScanCondition condition = ScanCondition::ExactValue;
+    int valueSize = 4;              // bytes per value (for unknown scans)
+};
+
+struct ScanResult {
+    uint64_t   address;
+    QString    regionModule;
+    QByteArray scanValue;       // cached bytes at scan/update time
+    QByteArray previousValue;   // value before last update
+};
+
 // ── Pattern parsing ──
 
 // Parse IDA-style signature string ("48 8B ?? 05") into pattern + mask.
@@ -57,6 +71,9 @@ bool serializeValue(ValueType type, const QString& input,
 // Natural alignment for a value type (used as default alignment for value scans).
 int naturalAlignment(ValueType type);
 
+// Byte-size for a value type (used for unknown scans and rescan read size).
+int valueSizeForType(ValueType type);
+
 // ── Scan engine ──
 
 class ScanEngine : public QObject {
@@ -67,6 +84,8 @@ public:
     void start(std::shared_ptr<Provider> provider, const ScanRequest& req);
     void startRescan(std::shared_ptr<Provider> provider,
                      QVector<ScanResult> results, int readSize,
+                     ScanCondition condition = ScanCondition::ExactValue,
+                     ValueType valueType = ValueType::Int32,
                      const QByteArray& filterPattern = {},
                      const QByteArray& filterMask = {});
     void abort();
@@ -82,6 +101,7 @@ private:
     QVector<ScanResult> runScan(std::shared_ptr<Provider> prov, const ScanRequest& req);
     QVector<ScanResult> runRescan(std::shared_ptr<Provider> prov,
                                    QVector<ScanResult> results, int readSize,
+                                   ScanCondition condition, ValueType valueType,
                                    const QByteArray& filterPattern,
                                    const QByteArray& filterMask);