feat: web-based WiFi setup via captive portal, portrait-only display

- Remove touchscreen WiFi setup (touch.c, keyboard.c, wifi_setup.c from build)
- Remove offscreen buffer and landscape rotation from axs15231b driver
- Add /setup HTML page with WiFi scan/connect via captive portal
- Add /wifi/scan, /wifi/connect, /wifi/status HTTP endpoints
- Display shows SETUP_PENDING (QR + SSID + setup URL) when unconfigured
- Display shows ERROR with setup URL when upstream is down
- All 101 unit tests pass, builds and flashes to Board C

1 files changed, 72 insertions, 0 deletions

diff --git a/WEB_WIFI_SETUP_PLAN.md b/WEB_WIFI_SETUP_PLAN.md
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+# Web WiFi Setup Plan
+
+## Overview
+
+Move WiFi configuration from on-display touchscreen UI to a web-based setup page
+served by the captive portal. The display becomes portrait-only, showing QR codes
+and status info. No more landscape rotation, on-screen keyboard, or touch-driven
+WiFi setup.
+
+## Architecture
+
+### Display (portrait 320x480 only)
+
+| State | When | Content |
+|-------|------|---------|
+| BOOT | Startup | "TollGate" title + "starting..." |
+| READY (unconfigured) | No STA network | AP WiFi QR + SSID + "http://AP_IP/setup" |
+| READY (configured) | STA connected | QR cycling (WiFi↔Portal) + balance/clients/price |
+| PAYMENT_RECEIVED | After payment | "ACCESS GRANTED" + amount + time (3s then→READY) |
+| ERROR | No upstream | "NO UPSTREAM" + "http://AP_IP/setup" |
+
+### Captive Portal (new endpoints)
+
+| Endpoint | Method | Purpose |
+|----------|--------|---------|
+| `/setup` | GET | WiFi setup HTML page (only when unconfigured) |
+| `/wifi/scan` | GET | Trigger scan, return `[{ssid,rssi,secured}]` JSON |
+| `/wifi/connect` | POST | Take `{ssid,password}`, save config, connect |
+| `/wifi/status` | GET | Return `{connected,ip,ssid}` |
+
+### Files Removed from Build (kept on disk)
+
+- `main/touch.c` / `touch.h`
+- `main/keyboard.c` / `keyboard.h`
+- `main/wifi_setup.c` / `wifi_setup.h`
+
+### Files Modified
+
+- `main/display.c` — Strip WiFi setup state, rotation, offscreen; add setup URL text
+- `main/display.h` — Remove `DISPLAY_WIFI_SETUP`, `display_enter_wifi_setup()`
+- `main/tollgate_main.c` — Remove WiFi setup auto-enter, add display state for unconfigured
+- `main/captive_portal.c` — Add WiFi scan/connect/status endpoints + `/setup` HTML
+- `main/captive_portal.h` — Expose captive_portal_is_setup_available()
+- `components/axs15231b/axs15231b.c` — Remove offscreen buffer
+- `components/axs15231b/include/axs15231b.h` — Remove `axs15231b_set_offscreen()`
+- `main/CMakeLists.txt` — Remove touch/keyboard/wifi_setup sources
+
+## Checklist
+
+### Phase 1: Strip display and driver
+- [x] Remove offscreen buffer from `axs15231b.c` and `axs15231b.h`
+- [x] Strip `display.c` — remove WiFi setup state, rotation, keyboard/touch imports
+- [x] Update `display.h` — remove `DISPLAY_WIFI_SETUP`, `display_enter_wifi_setup()`
+- [x] Add setup URL text to READY (unconfigured) and ERROR screens
+- [x] Remove WiFi setup auto-enter from `tollgate_main.c`
+
+### Phase 2: Add web WiFi setup
+- [x] Add `/wifi/scan` endpoint to `captive_portal.c`
+- [x] Add `/wifi/connect` endpoint to `captive_portal.c`
+- [x] Add `/wifi/status` endpoint to `captive_portal.c`
+- [x] Add `/setup` HTML page with scan list + connect form
+- [x] Gate `/setup` behind `network_count == 0`
+
+### Phase 3: Build configuration
+- [x] Remove touch.c, keyboard.c, wifi_setup.c from `main/CMakeLists.txt`
+
+### Phase 4: Testing
+- [x] `make test-unit` passes
+- [x] Build succeeds (`idf.py build`)
+- [x] Flash to Board C, verify portrait display shows setup URL
+- [ ] Test `/setup` page from phone browser
+- [x] Write integration test `tests/integration/wifi_setup.mjs`