Initial commit: MIKILAB KiCad personal library

Self-contained KiCad library (symbols, footprints, 3D models, docs,
import/check tooling) with no dependency on kicad-personal-library.

- Fixed sym-lib-table/fp-lib-table: single (version 7) header, one entry
  per library, MIKILAB_<name> nicknames, ${KIPRJMOD}-relative URIs
- Resolved the SOT95P280X145-5N footprint collision (TPS7A2012PDBVR vs
  TPS7A2018PDBVR): confirmed byte-identical modulo KiCad's internal
  tedit timestamp, unified into one shared footprint
- Resolved a case-insensitive filename collision between the official
  Diode.kicad_sym and a custom diode.kicad_sym
- Wrapped standalone footprints (ESP32-S31-WROOM-3, IC_TPS63020DSJT,
  SOT95P280X145-5N) into their own .pretty libraries so they're
  actually registered in fp-lib-table
- Fixed broken symbol->footprint references (including one pointing at
  a nonexistent easyeda2kicad library)
- Added scripts/check_library.py, import_component.py, add_component.py,
  import_batch.py, and lib_common.py

docs/README_2.md

@@ -0,0 +1,22 @@
+# ESP32-S31-WROOM-3
+
+KiCad schematic symbol and footprint for the ESP32-S31-WROOM-3 module.
+
+Note: this chip isn't widely available yet, but the symbol and footprint are ready if you want to start designing boards around it.
+
+## Contents
+
+- `ESP32-S31-WROOM-3.kicad_sym` — schematic symbol
+- `footprint/ESP32-S31-WROOM-3.kicad_mod` — PCB footprint
+
+## Usage
+
+Add this repo as a library in KiCad (Preferences > Manage Symbol Libraries / Manage Footprint Libraries), pointing at the `.kicad_sym` file and the `footprint` folder.
+
+## Preview
+
+### Schematic symbol
+![Schematic](schematic.png)
+
+### Footprint
+![Footprint](footprint.png)