agent: lumotia-rebrand — fix Codex cross-model review blockers

Codex independent review found 11 blockers post-cascade. All addressed.

CRITICAL (data-loss / crash):

10. crates/core/src/paths.rs — migrate_legacy_data_dir_inner used
    fs::rename which fails with EXDEV when source + target are on
    different filesystems (encrypted-home, bind mounts, separate
    $XDG_DATA_HOME partition). Combined with the Phase 5 QC fix that
    made migration errors fatal, this would crash on first launch
    for any user whose data dir spans filesystems. Added
    rename_or_copy_tree() that falls back to copy_dir_recursive +
    remove_dir_all on CrossesDevices / errno 18 (EXDEV). Symlinks
    preserved verbatim. Same fallback applied to magnotia.db ->
    lumotia.db inside the dir.

11. Added 4 unit tests: copy_dir_recursive preserves nested
    structure, rename_or_copy_tree same-filesystem happy path,
    is_cross_device classifies CrossesDevices kind + raw errno 18.

Doc residuals (blockers 1-9):

1. crates/cloud-providers/Cargo.toml — "Wyrdnote pending rebrand"
   description.
2. crates/cloud-providers/src/provider.rs — module docs + test
   fixture Wyrdnote refs.
3. crates/transcription/src/orchestrator.rs — module docs + test
   fixture Wyrdnote refs.
4. docs/roadmap/2026-05-10-pkm-phase-tooling-shortlist.md — phase
   name + outputs/wyrdnote path refs.
5. docs/architecture-map/04-llm-formatting-mcp/llm-tests.md —
   MAGNOTIA_LLM_TEST_MODEL env var.
6. .../cloud-providers-stubs.md — MAGNOTIA_API_KEY_*.
7. docs/architecture-map/03-audio-transcription/tests-and-fixtures.md
   — MAGNOTIA_WHISPER_*.
8. docs/gpu-tuning/plan.md — MAGNOTIA_BENCH_RUN.
9. docs/superpowers/specs/2026-05-09-battery-gpu-aware-thread-tuning-
   design.md + corresponding plan — MAGNOTIA_POWER_STATE_OVERRIDE,
   MAGNOTIA_INFERENCE_THREADS.

cargo test --workspace: 343 pass / 0 fail (up from 339; +4 EXDEV
fallback tests).

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

crates/cloud-providers/Cargo.toml

@@ -2,7 +2,7 @@
 name = "lumotia-cloud-providers"
 version = "0.1.0"
 edition = "2021"
-description = "Provider trait and BYOK cloud STT scaffolding for Lumotia (Wyrdnote pending rebrand)"
+description = "Provider trait and BYOK cloud STT scaffolding for Lumotia (Lumotia)"
 
 [dependencies]
 lumotia-core = { path = "../core" }

crates/cloud-providers/src/provider.rs

@@ -6,7 +6,7 @@
 //!
 //! Living in `lumotia-cloud-providers` is deliberate: the AGPL OEM
 //! exception (≥£2k/yr) requires a clean trait surface that an OEM
-//! licensee can implement without depending on Wyrdnote's transcription
+//! licensee can implement without depending on Lumotia's transcription
 //! internals. The trait crate stays small; provider implementations
 //! sit alongside.
 //!
@@ -175,10 +175,10 @@ mod tests {
             engine_id: ProviderId::new("local-whisper"),
             model_id: None,
             language: Some("en".to_string()),
-            initial_prompt: Some("Wyrdnote".to_string()),
+            initial_prompt: Some("Lumotia".to_string()),
         };
         let opts = profile.to_options();
         assert_eq!(opts.language, Some("en".to_string()));
-        assert_eq!(opts.initial_prompt, Some("Wyrdnote".to_string()));
+        assert_eq!(opts.initial_prompt, Some("Lumotia".to_string()));
     }
 }