Import measurement data from buildfor_life_web

Lamp SPD/TM-30/metrics for four EANs and solar charge controller
efficiency sweeps, moved out of the web repo so measurement data
lives in its own history.

README.md

@@ -0,0 +1,35 @@
+# comparison-data
+
+Raw measurement data behind [buildfor.life/comparisons](https://buildfor.life/comparisons).
+
+This repo is consumed by [buildfor_life_web](https://git.b4l.co.th/B4L/buildfor_life_web)
+as a git submodule at `apps/web/comparison-data`. At build time the site copies it to
+`/data/comparisons/`, where every file is both chart input and a raw download. Directory
+names are the keys the site's device pages reference in their `csv:` front matter, so
+renaming a directory here requires updating the matching page in the web repo.
+
+## Layout
+
+```
+lamps/<EAN>/spd.csv         SPD 380-1050 nm: wavelength_nm,value
+lamps/<EAN>/tm30.csv        ANSI/IES TM-30-18 per-hue-bin data (16 bins): Rcs, Rhs, Rf_h, ...
+lamps/<EAN>/metrics.json    Summary: TM-30 Rf/Rg, CRI Ra + R1-R15, CCT, flux, instrument metadata
+solar-charge-controllers/<device>.csv   Efficiency sweep: set/measured Vin, Iin, Pin, Vout,
+                                        Iout, Pout, eff_pct, heatsink and board temperature
+```
+
+Lamps are identified by their EAN barcode so results stay unambiguous across brands and
+packaging variants. EANs starting with 2 are retailer-internal barcodes that cannot be
+resolved publicly.
+
+## Provenance
+
+- Lamps: HPCS-6500 integrating sphere, 230 V / 50 Hz, five consecutive readings averaged
+  after stabilization. Instrument driver and TM-30 tooling:
+  [HPCS6500-py](https://git.b4l.co.th/B4L/HPCS6500-py). Procedure:
+  [lamp test procedure](https://buildfor.life/docs/tooling/lamp-test-procedure/).
+- Solar charge controllers: automated MPPT testbench sweeps. Procedure:
+  see the linked test procedure on the comparison page.
+
+Data is published as measured; files are never edited after the fact. Corrections happen
+by re-measuring and replacing the whole device directory in one commit.