Remove dead code (#11082)

Removed:
- MessageStore::addFromPacket and addFromString, superseded by
  tryAddFromPacket
- GeoCoord rangeRadiansToMeters, distanceTo, bearingTo
- Router::rawSend, declared virtual with no override and no caller
- ContentHandler handleHotspot, handleFs, handleAdminSettings,
  handleAdminSettingsApply, handleDeleteFsContent and their commented
  route registrations, plus the now unreachable htmlDeleteDir and the
  handleUpdateFs declaration that had no definition
- ContentHelper replaceAll
- OnScreenKeyboardModule popup chain: showPopup, clearPopup, drawPopup,
  drawPopupOverlay and their state, unreachable since the frame based UI
  was replaced by baseUI
- DebugRenderer drawDebugInfoTrampoline, drawDebugInfoSettingsTrampoline
  and the orphaned drawFrameSettings
- NodeListRenderer calculateMaxScroll, drawColumns and a stale extern
  haveGlyphs declaration with no definition
- UIRenderer::haveGlyphs, Screen::blink,
  NotificationRenderer::showKeyboardMessagePopupWithTitle,
  VirtualKeyboard::getInputText
- InkHUD touchNavLeft, touchNavRight, Applet::getActiveNodeCount,
  ThreadedMessageApplet::saveMessagesToFlash
- TwoButton::setHandlerUp, TwoButtonExtended setHandlerUp,
  setJoystickDownHandlers, setJoystickUpHandlers
- CannedMessageModule LaunchRepeatDestination, isCharInputAllowed,
  hasMessages
- TrafficManagementModule resetStats, recordRouterHopPreserved,
  saturatingIncrement
- UnitConversions::MetersPerSecondToMilesPerHour
- EncryptedStorage getSessionRemainingSeconds
- BMI270Sensor::writeRegisters, GPS::hasFlow, FSCommon copyFile,
  SerialConsole consolePrintf, buzz playLongPressLeadUp,
  memGet displayPercentHeapFree

src/security/EncryptedStorage.cpp

@@ -1078,16 +1078,6 @@ bool isSessionExpired()
     return (millis() - s_sessionStartedMs) > s_sessionMaxMs;
 }
 
-uint32_t getSessionRemainingSeconds()
-{
-    if (s_sessionMaxMs == 0)
-        return 0;
-    uint32_t elapsedMs = millis() - s_sessionStartedMs;
-    if (elapsedMs >= s_sessionMaxMs)
-        return 0;
-    return (s_sessionMaxMs - elapsedMs) / 1000UL;
-}
-
 uint8_t consumeSessionBoot()
 {
     if (s_bootsRemaining == 0) {

src/security/EncryptedStorage.h

@@ -243,10 +243,6 @@ void setSession(uint32_t maxSeconds);
 /// from the main loop on a low-frequency tick.
 bool isSessionExpired();
 
-/// Seconds remaining in the current session. 0 if no timer is set, or if
-/// the timer has expired (use isSessionExpired() to distinguish).
-uint32_t getSessionRemainingSeconds();
-
 /// Consume one boot from the on-flash token (the rollback ledger) and
 /// re-arm the session timer in place - no reboot. Called from the main
 /// loop when a session expires AND there is still budget. Decrements