Add WiFi/HTTP transport variant (alongside USB CDC)

[dsk2k]

Adds a third host↔board transport option — WiFi/HTTP — alongside main's BLE and @dilbery's PR #26 USB CDC. Daemon publishes an HTTP bridge on the host LAN, board polls it over WiFi. Compile-time selectable via build flag so existing setups don't change unless they opt in.

Tested on real hardware

Board: Waveshare ESP32-S3-Touch-AMOLED-2.16 (480×480).
Host: Windows 10 (Dutch locale), Python 3.14, PlatformIO 6.1.19.
Network: standard home WiFi (2.4GHz), board → AP → host on the same /24.

Verified end-to-end:

• Daemon publishes payload at http://<host>:8787/payload with bearer-token auth (token persists in ~/.clawdmeter/wifi_token, mode 0600 on POSIX). /health is open for diagnostics.
• Firmware connects to WiFi STA, polls the bridge every 5s (configurable WIFI_POLL_MS), parses the same JSON schema as USB CDC, renders Usage + Activity exactly as on the other transports.
• netstat audit on host: 24 concurrent TimeWait entries from the board's IP on port 8787, ~5 new unique source ports every 25s. Matches WIFI_POLL_MS = 5000 exactly.
• Physical USB-unplug test: USB-C cable pulled from the host, board moved to a wall-charger. Daemon log shows the USB CDC writer recycling its port and falling through to run_session_no_port() (HTTP-only mode). Board continues receiving Usage + Activity live, polling over WiFi only.

Scope of this PR

Built on top of @dilbery's PR #26 (USB CDC transport) plus my Windows-port and Activity backport from those discussions, so this branch carries some commits that aren't WiFi-specific. The WiFi-only delta is the single commit 36d97d0 — 9 files, 423 insertions:

• firmware/src/wifi_link.{h,cpp} (new) — public API mirrors serial_link.h, body wrapped in #ifdef CLAWDMETER_TRANSPORT_WIFI so USB-only builds don't need wifi_config.h.
• firmware/src/wifi_config.h.example — template, real wifi_config.h is .gitignored.
• firmware/src/main.cpp — macro layer (link_init → serial_link_init or wifi_link_init) so the rest of main.cpp doesn't change between transports.
• firmware/src/ui.h — conditional include for the active transport's link_state_t.
• firmware/platformio.ini — new env waveshare_amoled_216_wifi extends the USB env + -DCLAWDMETER_TRANSPORT_WIFI.
• daemon/claude_usage_daemon.py — stdlib http.server.ThreadingHTTPServer thread; _http_payload_lock-guarded cache; helper run_session_no_port() keeps API + state.json polling alive when there's no USB port.
• daemon/run-daemon.ps1 — sets CLAWDMETER_HTTP=1 for Windows scheduled-task runs.
• .gitignore — excludes wifi_config.h.

Design notes

• Decoupling: update_http_payload() runs unconditionally during payload assembly, so a USB CDC write failure doesn't take HTTP down (and vice versa). Both transports serve the same data without doubling the upstream API hit rate.
• Token handling: stdlib secrets.token_urlsafe(32) at first daemon start, secrets.compare_digest() for constant-time validation. POSIX chmod 0o600 on the token file; on Windows the default user-profile ACL is sufficient.
• No HTTPS — bridge is LAN-only, same threat model as @dilbery's USB-only path. Don't expose to the Internet without a reverse proxy.
• Architecture precedent: same shape as rootedlab-code/claude-code-usage-monitor (different host-side data source, same transport pattern). Their bearer-token + LAN HTTP + 5s poll approach worked, ours follows.

Known follow-ups

• First-time WiFi setup is compile-time only. rootedlab-code uses a captive portal on softAP (board boots as ClaudeMonitor-XXYY until configured). Doable here too — Arduino WiFi has the primitives — but kept out of this PR to keep the diff focused. Hardcoded wifi_config.h works for personal-use scenarios.
• Daemon serves both transports simultaneously, which produces benign Write failed; recycling port log spam when the board is on WiFi-only. A future cleanup is a CLAWDMETER_TRANSPORT={USB,WIFI,BOTH} env-var split; for now both modes coexist.

How to use

# Host side
export CLAWDMETER_HTTP=1               # (or set in run-daemon.ps1 on Windows)
./install-mac.sh                       # or your platform's installer
# Daemon prints bearer token at startup:
#   "WiFi-bridge token: <copy this into wifi_config.h>"

# Firmware side
cp firmware/src/wifi_config.h.example firmware/src/wifi_config.h
# Edit wifi_config.h with SSID / password / host IP / token
pio run -e waveshare_amoled_216_wifi -t upload

Happy to split this into a smaller cleaner PR off main (or a stacked PR against #26) if that's easier to review — let me know what works.

[alasdaircs]

Related: I built a variant that takes a different architectural position — the ESP32 calls the Anthropic API directly over Wi-Fi using a long-lived token, so there's no host daemon at all (not even an HTTP bridge). The BLE HID keyboard is kept for the physical buttons; the GATT data service is removed.

It also implements the captive-portal provisioning you flagged as a known follow-up: on first boot the device starts a softAP named "ClawdMeter", serves a setup form at 192.168.4.1, and stores credentials to NVS. Re-provisioning is triggered from a Wi-Fi screen on the device.

Fork is here if it's useful context: https://github.com/alasdaircs/clawdmeter-wifi

@HermannBjorgvin I'm happy to leave it as a standalone fork — just wanted to surface it given the overlap with this issue. If a PR that adds this as an opt-in build env would be welcome, say the word and I'll write one up properly.