Add VoiceNotes firmware and CDM customer service SQL project

VoiceNotes is an Arduino sketch for the Waveshare ESP32-C6-LCD-0.85 that
records meetings and voice memos to microSD and turns them into notes:

- Records 16 kHz mono WAV (up to 4 h) from the ES7210 dual mics, with a
  boosted preamp and soft-limited digital gain
- Transcribes via an OpenAI-compatible speech-to-text API in ~10 min parts
  cut at quiet points, with retries and resume after failures
- Summarizes the transcript with Claude into meeting notes (decisions,
  action items, topics with timestamps), streamed to and from the card
- Copies the notes to Nextcloud over WebDAV
- Shows recording/processing state on the 0.85" LCD and the LED ring
- Works around the board's SD card failing multi-sector reads

Credentials live in VoiceNotes/secrets.h, which is git-ignored; see
secrets.example.h.

Also adds the Microsoft CDM customer service SQL implementation (DDL,
sample data, reporting queries and docs). Its README is renamed to
CDM_README.md so the repository README stays at the top level.

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

VoiceNotes/config.h

@@ -0,0 +1,73 @@
+// Board pinout and app settings for the Waveshare ESP32-C6-LCD-0.85.
+// Pins come from Waveshare's schematic and demo code:
+// https://github.com/waveshareteam/ESP32-C6-LCD-0.85
+#pragma once
+
+// ---------- Buttons (active LOW, external pull-ups on the board) ----------
+// The board has only two GPIO buttons. The PWR key drives the power switch IC
+// and is not readable from firmware.
+#define PIN_BTN_PLUS   18   // "PLUS" key  -> Button 1: start recording
+#define PIN_BTN_BOOT    9   // "BOOT" key  -> Button 2: stop recording
+// Button 3 (transcribe + summarize) defaults to a long-press of PLUS.
+// If you wire an external push button (to GND), set its GPIO here and it
+// will also act as Button 3 on a single click. -1 = not fitted.
+#define PIN_BTN_EXTRA  -1
+#define BTN3_LONG_PRESS_MS 1000
+
+// ---------- LCD: ST7735, 128x128, shares the SPI bus with the microSD ----------
+#define PIN_SPI_SCK     1
+#define PIN_SPI_MOSI    2
+#define PIN_SPI_MISO   16
+#define PIN_LCD_DC      3
+#define PIN_LCD_CS      5
+#define PIN_LCD_RST     4
+#define PIN_LCD_BL      6
+#define LCD_COL_OFFSET  2
+#define LCD_ROW_OFFSET  3
+
+// ---------- microSD ----------
+#define PIN_SD_CS      17
+#define SD_SPI_HZ      20000000
+
+// ---------- LED ring: 8 x WS2812B ----------
+#define PIN_LEDS       14
+#define NUM_LEDS        8
+#define LED_BRIGHTNESS 60     // 0-255; the ring is bright at close range
+#define LED_COLOR_ORDER RGB   // per Waveshare's demo; use GRB if red and green look swapped
+
+// ---------- Audio: ES7210 mic ADC on I2C + I2S ----------
+#define PIN_I2C_SDA     8
+#define PIN_I2C_SCL     7
+#define PIN_I2S_MCLK   19
+#define PIN_I2S_BCLK   20
+#define PIN_I2S_WS     22
+#define PIN_I2S_DIN    21     // ES7210 SDOUT1 -> ESP32
+#define PIN_PA_CTRL    15     // NS4150 speaker amp enable (kept off)
+#define ES7210_ADDR  0x40
+#define MIC_GAIN_STEP  14     // ES7210 PGA: 0..10 = 0..30 dB in 3 dB steps, 11..14 = 33/34.5/36/37.5 dB (max)
+#define DIGITAL_GAIN_DB 6     // extra software gain after the preamp, with a soft limiter (0 = off)
+
+#define SAMPLE_RATE 16000     // 16 kHz mono 16-bit = 32 KB/s, ideal for speech-to-text
+
+// Longest recording (also limited by free space on the card). 4 h = ~460 MB.
+#define MAX_RECORD_SECONDS (4 * 3600)
+
+// Transcription APIs reject files over 25 MB (~13 min), so long recordings are
+// sent in parts of about STT_SEGMENT_SECONDS each. Every cut is moved to the
+// quietest moment in the CUT_SEARCH_SECONDS before it, so words aren't split.
+#define MAX_UPLOAD_BYTES    (25UL * 1024 * 1024)
+#define STT_SEGMENT_SECONDS 600
+#define CUT_SEARCH_SECONDS  15
+#define STT_MAX_ATTEMPTS    3      // per part, before giving up (progress is kept for a later resume)
+
+// ---------- Network ----------
+// DNS servers used instead of the ones the router hands out ("" = keep the router's).
+// Pinned because the board was once seen using 8.8.8.9, which doesn't answer DNS and
+// added ~8 s to every connection.
+#define DNS_PRIMARY   "8.8.8.8"
+#define DNS_SECONDARY "1.1.1.1"
+
+// ---------- Storage layout ----------
+#define DIR_RECORDINGS "/recordings"
+#define DIR_NOTES      "/notes"
+#define LAST_REC_FILE  "/recordings/last.txt"