agent: lumotia-rebrand — fix QC blockers for phase 2

Phase 2 QC found three explicit blockers + a broader sweep needed:

Explicit (QC-named):
- crates/mcp/src/lib.rs:15 — SERVER_NAME public MCP wire identity
- crates/transcription/build.rs:59 — panic message prefix
- crates/llm/tests/content_tags_smoke.rs:7 — docstring -p flag

Swept (string literals + dev env vars + doc comments + test fixtures):
- crates/mcp/src/main.rs — eprintln log prefixes
- src-tauri/src/commands/diagnostics.rs — diagnostic filename + MAGNOTIA_VERSION
- src-tauri/src/commands/audio.rs — recording filename pattern lumotia-<secs>-...wav
- src-tauri/src/commands/fs.rs — test placeholder path
- crates/transcription/src/model_manager.rs — .lumotia-verified marker
- crates/storage/src/database.rs — lumotia-storage-ro-<pid> temp dirs + doc comments
- crates/cloud-providers/src/keystore.rs — LUMOTIA_API_KEY_<PROVIDER> env var
- crates/audio/src/{wav,decode}.rs — lumotia_test_* / lumotia_decode_* test fixtures
- crates/core/src/tuning.rs — LUMOTIA_INFERENCE_THREADS env var
- All MAGNOTIA_LLM_TEST_MODEL / MAGNOTIA_WHISPER_TEST_* env vars
- Doc comments referencing crate names

Excluded (intentional Phase 4/5 scope):
- magnotia_preferences, magnotia_history, magnotia_morning_triage_last_shown
  DB setting keys (Phase 5 paths.rs migration)
- magnotia_startup tracing target (Phase 4)
- crates/core/src/paths.rs (Phase 5 wholesale rewrite + migration shim)

cargo build --workspace passes. cargo test --workspace: 330 pass, 0 fail.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/audio/src/wav.rs

@@ -182,7 +182,7 @@ mod tests {
         // mirrors what happens when the OS reaps the process without
         // giving Rust a chance to run destructors.
         let temp_dir = std::env::temp_dir();
-        let path = temp_dir.join("magnotia_test_wav_writer_survives_crash.wav");
+        let path = temp_dir.join("lumotia_test_wav_writer_survives_crash.wav");
         let _ = std::fs::remove_file(&path);
 
         let mut writer = WavWriter::create(&path, 16_000, 1).unwrap();
@@ -219,7 +219,7 @@ mod tests {
     #[test]
     fn wav_writer_append_then_finalize_roundtrips() {
         let temp_dir = std::env::temp_dir();
-        let path = temp_dir.join("magnotia_test_wav_writer_finalize.wav");
+        let path = temp_dir.join("lumotia_test_wav_writer_finalize.wav");
         let _ = std::fs::remove_file(&path);
 
         let mut writer = WavWriter::create(&path, 16_000, 1).unwrap();
@@ -241,7 +241,7 @@ mod tests {
         // truncated WAV returned Ok with a short samples vec. The
         // new code must propagate the error.
         let temp_dir = std::env::temp_dir();
-        let path = temp_dir.join("magnotia_test_truncated_wav.wav");
+        let path = temp_dir.join("lumotia_test_truncated_wav.wav");
         let _ = std::fs::remove_file(&path);
 
         // Write 100 samples (200 bytes at 16-bit).
@@ -267,7 +267,7 @@ mod tests {
     #[test]
     fn wav_roundtrip() {
         let temp_dir = std::env::temp_dir();
-        let path = temp_dir.join("magnotia_test_roundtrip.wav");
+        let path = temp_dir.join("lumotia_test_roundtrip.wav");
 
         let original = AudioSamples::mono_16khz(vec![0.0, 0.5, -0.5, 0.25, -0.25]);
         write_wav(&path, &original).unwrap();