Fix TWDT starvation, vsync race, and UI responsiveness from review

Three bugs and two UX defects found on review, plus hardening:

- The control loop fed the task watchdog then slept exactly the watchdog
  period (both 10s), tripping the TWDT fractionally late on every single
  iteration. Sleep is now sliced 1s with a reset per slice. Also set
  CONFIG_ESP_TASK_WDT_PANIC=y - the sdkconfig comment claimed a hung task
  panics the chip, but nothing actually made that true.

- The LVGL flush called draw_bitmap (which only queues the framebuffer
  switch) and released LVGL immediately, letting it render the next frame
  into the buffer still being scanned out - the exact PRD 8.2 race the
  double-buffer design exists to prevent. display_present_frame() now
  blocks on a vsync handshake until the swap has latched.

- WiFi reconnect slept up to 30s inside the system event handler, stalling
  all queued WiFi/IP events. Moved to an esp_timer.

- The setpoint label, arc, and mode/room lines rendered the control loop's
  copy of state, which refreshes every 10s - every knob detent looked dead
  for up to 10 seconds. The UI now reads settings live; when the fallback
  ladder clamps the setpoint it shows both values. Room-select focus now
  shows which room is being selected.

- z2m ISO_8601_local timestamps carry a UTC offset the parser ignored,
  which would shift apparent reading age by the local offset (5-6h in the
  US) and permanently trip the fallback ladder. Offset is now honoured.

- Suppressed the cosmetic "control loop stopped" fault in the window
  between relay_init and the control task's first call-in at boot.

- Explicit pullups on the encoder A/B lines.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

main/drivers/encoder/encoder.c

@@ -1,5 +1,6 @@
 #include "encoder.h"
 
+#include "driver/gpio.h"
 #include "driver/pulse_cnt.h"
 #include "esp_check.h"
 #include "esp_log.h"
@@ -125,6 +126,16 @@ esp_err_t encoder_init(void)
                                       PCNT_CHANNEL_LEVEL_ACTION_INVERSE),
         TAG, "chan b level");
 
+    /*
+     * The vendor's Arduino example uses bare INPUT, implying external pullups
+     * on the board, but their ESPHome config enables internal ones as well.
+     * Enabling them here costs nothing and guards against a floating line
+     * reading as phantom rotation. (Done after channel creation so the PCNT
+     * driver's own GPIO setup cannot undo it.)
+     */
+    gpio_pullup_en(ENCODER_PIN_A);
+    gpio_pullup_en(ENCODER_PIN_B);
+
     ESP_RETURN_ON_ERROR(pcnt_unit_enable(s_unit), TAG, "enable");
     ESP_RETURN_ON_ERROR(pcnt_unit_clear_count(s_unit), TAG, "clear");
     ESP_RETURN_ON_ERROR(pcnt_unit_start(s_unit), TAG, "start");