fix(lockscreen): correct main.cpp injection anchor and early-return guard

plugins/lockscreen/LockscreenActivity.h

@@ -0,0 +1,65 @@
+#pragma once
+
+#include "activities/settings/LockscreenPlugin.h"
+#include "activities/Activity.h"
+
+class LockscreenActivity final : public Activity {
+ public:
+    enum class Purpose { UNLOCK, CREATE };
+
+    static constexpr int COLS = 3;
+    static constexpr int ROWS = 4;
+
+    explicit LockscreenActivity(GfxRenderer& renderer,
+                                MappedInputManager& mappedInput,
+                                Purpose purpose)
+        : Activity("Lockscreen", renderer, mappedInput), purpose_(purpose) {}
+
+    void onEnter() override;
+    void onExit() override;
+    void loop() override;
+    bool skipLoopDelay() override { return true; }
+    void render(RenderLock&&) override;
+
+    bool wasSuccessful() const { return success_; }
+    bool isDone() const { return done_; }
+    bool needsRender() const { return renderPending_; }
+
+    void renderDirect() {
+        renderPending_ = false;
+        RenderLock rl(*this);
+        render(std::move(rl));
+    }
+
+ private:
+    static constexpr int PIN_LEN = 4;
+    static constexpr unsigned long TIMEOUT_MS = 120000;
+
+    static constexpr const char* KEYS[ROWS][COLS] = {
+        {"1", "2", "3"},
+        {"4", "5", "6"},
+        {"7", "8", "9"},
+        {"<", "0", "OK"},
+    };
+
+    Purpose purpose_;
+    bool    success_       = false;
+    bool    done_          = false;
+    bool    renderPending_ = false;
+
+    int cursorRow_ = 0;
+    int cursorCol_ = 0;
+
+    char pin_[PIN_LEN + 1] = {};
+    int  pinLen_            = 0;
+
+    int attempts_ = 0;
+    static constexpr int MAX_ATTEMPTS = 3;
+
+    unsigned long enterTime_ = 0;
+
+    void pressCurrentKey();
+    void renderPinDisplay(int startY, bool masked) const;
+    void renderKeypad(int startY) const;
+    void goToSleep();
+};