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/build.rs

@@ -56,7 +56,7 @@ fn main() {
 
     if target_os == "windows" {
         panic!(
-            "magnotia-transcription: the `tokenizers` crate appears in Cargo.lock and this is a \
+            "lumotia-transcription: the `tokenizers` crate appears in Cargo.lock and this is a \
              Windows build. Linking `whisper-rs-sys` + `tokenizers` in the same binary has \
              been a persistent MSVC C-runtime conflict (see Whispering v7.11.0). Route any \
              tokenizer usage through an out-of-process sidecar instead, or gate it off for \
@@ -65,7 +65,7 @@ fn main() {
     }
 
     println!(
-        "cargo:warning=magnotia-transcription: `tokenizers` crate is in the dependency graph. \
+        "cargo:warning=lumotia-transcription: `tokenizers` crate is in the dependency graph. \
          This build is non-Windows so the link will succeed, but Windows builds will panic \
          at build time per docs/whisper-ecosystem/brief.md item #6. Isolate tokenizer usage \
          in a sidecar before a Windows ship."