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/secrets.example.h

@@ -0,0 +1,32 @@
+// Copy this file to secrets.h and fill in your values.
+// secrets.h is git-ignored so your keys stay off GitHub.
+#pragma once
+
+#define WIFI_SSID     "your-wifi-name"
+#define WIFI_PASSWORD "your-wifi-password"
+
+// POSIX timezone string used for the timestamp in file names.
+// Examples: "PST8PDT,M3.2.0,M11.1.0" (US Pacific), "EST5EDT,M3.2.0,M11.1.0" (US Eastern),
+//           "GMT0BST,M3.5.0/1,M10.5.0" (UK), "IST-5:30" (India), "UTC0"
+#define TIMEZONE "PST8PDT,M3.2.0,M11.1.0"
+
+// ---- Speech-to-text: any OpenAI-compatible /audio/transcriptions endpoint ----
+// OpenAI:  host "api.openai.com", path "/v1/audio/transcriptions", model "whisper-1"
+//          (or "gpt-4o-transcribe" / "gpt-4o-mini-transcribe")
+// Groq:    host "api.groq.com",   path "/openai/v1/audio/transcriptions", model "whisper-large-v3-turbo"
+#define STT_HOST    "api.openai.com"
+#define STT_PATH    "/v1/audio/transcriptions"
+#define STT_MODEL   "whisper-1"
+#define STT_API_KEY "sk-..."
+
+// ---- Summarization: Claude ----
+#define ANTHROPIC_API_KEY "sk-ant-..."
+#define CLAUDE_MODEL      "claude-opus-5-5"
+
+// ---- Nextcloud: finished notes are copied here (leave NEXTCLOUD_HOST "" to turn off) ----
+// Use an app password, not your login password:
+// Nextcloud -> Settings -> Security -> "Devices & sessions" -> Create new app password.
+#define NEXTCLOUD_HOST     ""              // e.g. "cloud.example.com"
+#define NEXTCLOUD_USER     ""
+#define NEXTCLOUD_PASSWORD ""            // paste the app password here
+#define NEXTCLOUD_FOLDER   "secondbrain"