Add LVSolarBuck64 firmware and debug console with uv support

STM32G474RB firmware for solar buck converter with MPPT, CC control,
Vfly compensation, and adaptive deadtime. Includes Textual TUI debug
console for real-time telemetry, parameter tuning, and SQLite logging.

Added pyproject.toml for uv: `cd code64 && uv run debug-console`

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

code64/Core/Src/PI.c

@@ -0,0 +1,37 @@
+/*
+ * cc_pid.c
+ *
+ *  Created on: Jun 10, 2025
+ *      Author: janik
+ */
+
+#include <PI.h>
+
+void PI_Init(PIController *pi, float Kp, float Ki, uint16_t out_min, uint16_t out_max)
+{
+    pi->Kp = Kp;
+    pi->Ki = Ki;
+    pi->prev_error = 0.0f;
+    pi->output = 0;
+    pi->out_min = out_min;
+    pi->out_max = out_max;
+}
+
+uint16_t PI_Update(PIController *pi, float target, float measurement)
+{
+    float error = target - measurement;
+    float delta = pi->Kp * (error - pi->prev_error) + pi->Ki * error;
+
+    // Add delta to the output (cast to float for calculation)
+    float new_output = (float)(pi->output) + delta;
+
+    // Clamp
+    if (new_output > (float)(pi->out_max)) new_output = (float)(pi->out_max);
+    else if (new_output < (float)(pi->out_min)) new_output = (float)(pi->out_min);
+
+    // Update internal state
+    pi->output = (uint16_t)new_output;
+    pi->prev_error = error;
+
+    return pi->output;
+}