M3 WIP: DSI bring-up + state machine + identity overlay

DSI / panel:
- LDO_VO3 acquired at 2500 mV (VDD_MIPI_DPHY) — without this the PHY
  PLL busy-waits forever inside esp_lcd_new_dsi_bus.
- PSRAM bumped to 200 MHz (CONFIG_IDF_EXPERIMENTAL_FEATURES) to keep
  the DPI fed without underruns.
- Pi-7"-style 800x480 panel init (REG_POWERON, PORTA/PORTB/PWM/PORTC)
  + 16-bit RGB565 framebuffer with portrait-mode rotation buffer in
  PSRAM. Currently shows garbled output — known issue, next commit
  switches to the TC358762-bridge-aware init sequence.

State + UX:
- viewport_state simplified to AWAKE/ASLEEP only; "unconfigured" is
  a flag, not a state. Tap always toggles; content choice (identity
  vs frame) is driven by the configured flag.
- BOOT button arms a 15 s identity overlay via local_screens_overlay;
  expired callback returns to prior state.
- Boot-done indicator: two backlight flashes (no usable LED GPIO on
  the Waveshare board — GPIO 35 BOOT is shared with EMAC TXD1).
- Best-effort subsystem init in app_main; display init deferred to
  its own task so a panel hang can't block networking.

Display test pattern: solid R/G/B for 2 s each on boot to characterize
the garble independent of text rendering.

1 files changed, 14 insertions, 6 deletions

diff --git a/main/local_screens.h b/main/local_screens.h
index ffe9a3d..f1e4876 100644
--- a/main/local_screens.h
+++ b/main/local_screens.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <stdbool.h>
+
 #include "esp_err.h"
 
 // Initialize the local-screen renderer. Allocates a PSRAM scratch buffer
@@ -20,9 +22,15 @@ esp_err_t local_screens_show_ip(void);
 // until the next /frame arrives.
 esp_err_t local_screens_show_loading(void);
 
-// Repaint the current best screen for `state`. Used after the BOOT-button
-// 15-second overlay expires.
-//   UNCONFIGURED -> IP screen
-//   ASLEEP       -> (caller handles backlight; this paints a black FB)
-//   AWAKE        -> black FB; Scrypted's next /frame restores live content
-esp_err_t local_screens_restore_for_state(void);
+// Show the identity ("who am I") screen for `duration_ms`, then drop the
+// backlight off. Used by the BOOT button short-press (any state) and by
+// the touch handler when the device is unconfigured.
+esp_err_t local_screens_overlay(uint32_t duration_ms);
+
+// True while the identity overlay is currently shown (timer armed).
+// Used by the touch handler to make a second tap dismiss the overlay
+// instead of re-arming it.
+bool local_screens_overlay_active(void);
+
+// Dismiss the overlay now: cancel the timer and drop the backlight.
+void local_screens_overlay_dismiss(void);