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/transcription/src/model_manager.rs

@@ -74,7 +74,7 @@ pub fn list_downloaded() -> Vec<ModelId> {
 /// For files that declare a `sha256` checksum we validate an existing
 /// complete file before skipping the download — a truncated or
 /// tampered file gets redownloaded automatically (pattern ported from
-/// `magnotia-llm`'s model_manager, item #8 in the Whisper ecosystem brief).
+/// `lumotia-llm`'s model_manager, item #8 in the Whisper ecosystem brief).
 pub async fn download(
     id: &ModelId,
     progress: impl Fn(DownloadProgress) + Send + 'static,
@@ -113,7 +113,7 @@ pub async fn download(
 }
 
 fn verified_manifest_path(dir: &Path) -> PathBuf {
-    dir.join(".magnotia-verified")
+    dir.join(".lumotia-verified")
 }
 
 fn verified_manifest_matches(
@@ -220,7 +220,7 @@ async fn download_file(
     // If we requested Range but the server returned 200 (full file), the
     // server does not support resume. Rather than blindly appending a
     // full file on top of our partial bytes (which would produce a
-    // corrupt result), restart cleanly. This mirrors the magnotia-llm
+    // corrupt result), restart cleanly. This mirrors the lumotia-llm
     // ResumeUnsupported branch — item #8 of the brief.
     //
     // For the non-resume path, we still have to validate the status: