Firmware version: <version.txt>-<git short hash>, starting at 0.0.1

e.g. 0.0.1-1d613b1: the first part is set by hand, the hash says which
commit was built. No dirty flag (the build always patches cspot).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -28,7 +28,7 @@ Repo: https://gitea.apointless.space/bsncubed/aes67-ESP32-P4
   - Rev < 3 also limits Espressif's prebuilt audio libraries: `esp_audio_codec` must stay < 2.6 and `esp_audio_effects` < 1.4 (newer versions use P4 assembly that needs rev >= 3; the build fails with a message saying so). Check this for any new Espressif binary component.
 - Embed `web/index.html` via `EMBED_TXTFILES` in `aes67_web`.
 - cspot (Spotify, `external/cspot` git submodule, philippe44 fork, pinned): after cloning run `git submodule update --init external/cspot && git -C external/cspot submodule update --init cspot/bell`. Its nanopb code generator needs, in the IDF Python env: `python -m pip install protobuf grpcio-tools 'setuptools<81'` (after `. export.sh`). Our fixes to cspot/bell live in `components/spotify/patches/{cspot,bell}/*.patch` and are applied automatically at configure time; don't edit the submodule directly, add a patch.
-- Firmware version: first line of `version.txt` (e.g. `0.9.0`). Bump it for a release; editing it is enough, the next build picks it up.
+- Firmware version: `<version.txt>-<git short hash>`, e.g. `0.0.1-1d613b1`. Bump `version.txt` for a release; the hash is the commit that was built (commit first, then build, so it matches). No dirty flag.
 - Flash over the network (normal way since step 2b; keep USB for recovery):
   `curl -f --data-binary @build/aes67_p4.bin -H 'Content-Type: application/octet-stream' http://p4-aes67/api/ota`
   The board reboots into the new image on trial; check `GET /api/ota` shows the new version with `pending_verify: false`.
@@ -44,7 +44,7 @@ Repo: https://gitea.apointless.space/bsncubed/aes67-ESP32-P4
 - On-die temperature sensor only (driver/temperature_sensor.h).
 
 ## Build order / status
-- [x] 0. Check chip revision and flash size; create IDF project and empty component stubs (layout in aes67-core-base.md). Set up the OTA partition table (two app slots, no factory) and PROJECT_VER now, so the layout never changes later. (PROJECT_VER comes from `version.txt`, set by hand.)
+- [x] 0. Check chip revision and flash size; create IDF project and empty component stubs (layout in aes67-core-base.md). Set up the OTA partition table (two app slots, no factory) and PROJECT_VER now, so the layout never changes later. (PROJECT_VER = `version.txt` + git short hash.)
 - [x] 1. Ethernet: IP101 up, DHCP, IP logged. Ping works.
 - [x] 2. Web server + config store (cJSON in NVS) + embedded index.html; /api/config, /api/status (stub values), /api/reboot.
 - [x] 2a. Finding the device: mDNS (hostname.local + _http._tcp), then LLDP (switch shows name + IP).