Left half schematic: matrix, MCU and passives placed

34 switches matching the 34-key layout, 68 diodes, 40 capacitors, the
crystal, MCU and connectors. 262 symbols total.

Committed with KiCad still open on the project - this is the last saved
state, not necessarily a finished edit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Schematics/Left/Tertiary_Left.kicad_pro

@@ -294,6 +294,7 @@
       "netlist": "",
       "plot": "",
       "specctra_dsn": "",
+      "step": "",
       "vrml": ""
     },
     "page_layout_descr_file": ""
@@ -416,7 +417,7 @@
         "uuid": "f79eb362-a6e9-4eda-a639-78c3eeb01ab8"
       }
     ],
-    "used_designators": "RN1,J11,C15-16,#PWR48-52",
+    "used_designators": "U1-2,R6,SW5-40,RN1,J6,J11,D2-75,C2,C7-51,Y1,#PWR4,#PWR25-157",
     "variants": []
   },
   "sheets": [