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>

docs/architecture-map/03-audio-transcription/tests-and-fixtures.md

@@ -48,17 +48,17 @@ All three skip silently if the env vars are unset, so `cargo test` on a fresh ma
 
 ### `whisper_rs_smoke.rs`
 
-- Env vars: `MAGNOTIA_WHISPER_TEST_MODEL` (path to a ggml/gguf Whisper model).
+- Env vars: `LUMOTIA_WHISPER_TEST_MODEL` (path to a ggml/gguf Whisper model).
 - Loads the context, builds a state, calls `set_initial_prompt("Wren, CORBEL, ADHD")` (proves the API still exists), runs inference on 1 s of silence, exercises `full_n_segments` and `get_segment(i).to_str()`. Smoke test only; assertion is "did this run without panicking".
 
 ### `jfk_bench.rs`
 
-- Env vars: `MAGNOTIA_WHISPER_TEST_MODEL`, `MAGNOTIA_WHISPER_TEST_AUDIO` (path to a 16 kHz mono 16-bit PCM WAV — assertions in the test enforce this format on the fixture, not the runtime).
+- Env vars: `LUMOTIA_WHISPER_TEST_MODEL`, `LUMOTIA_WHISPER_TEST_AUDIO` (path to a 16 kHz mono 16-bit PCM WAV — assertions in the test enforce this format on the fixture, not the runtime).
 - Reports cold-load time, cold-transcribe RTF, warm-transcribe RTF, peak RSS read from `/proc/{pid}/status`. Hardcodes `set_n_threads(6)` for both runs (so a sweep across thread counts is a separate test, not this one).
 
 ### `thread_sweep.rs`
 
-- Same env vars as `jfk_bench.rs`. Adds `MAGNOTIA_POWER_STATE_OVERRIDE` (set internally per panel to `ac` or `battery`) so `inference_thread_count` returns its predicted pick for each combination of (power state × GPU offload) and the empirical RTF table can be compared against the helper's choice.
+- Same env vars as `jfk_bench.rs`. Adds `LUMOTIA_POWER_STATE_OVERRIDE` (set internally per panel to `ac` or `battery`) so `inference_thread_count` returns its predicted pick for each combination of (power state × GPU offload) and the empirical RTF table can be compared against the helper's choice.
 - Runs the JFK clip at `n_threads = 1, 2, 4, physical, logical` (plus `8` if logical ≥ 8), takes the min of two runs per setting, prints a four-panel table:
   1. AC, CPU.
   2. AC, GPU (Vulkan).
@@ -69,9 +69,9 @@ All three skip silently if the env vars are unset, so `cargo test` on a fresh ma
 
 ## Watch-outs
 
-- **All three integration tests are quiet on missing env vars.** A green `cargo test` does NOT mean the Whisper path works; it means "either the path works or you didn't set the env vars". CI configurations must explicitly set `MAGNOTIA_WHISPER_TEST_MODEL` to exercise these.
+- **All three integration tests are quiet on missing env vars.** A green `cargo test` does NOT mean the Whisper path works; it means "either the path works or you didn't set the env vars". CI configurations must explicitly set `LUMOTIA_WHISPER_TEST_MODEL` to exercise these.
 - **`jfk_bench.rs` hardcodes `n_threads = 6`.** Production code uses `inference_thread_count(Workload::Whisper, gpu_offloaded)` which is power-aware. Bench numbers are not directly comparable to runtime numbers without rerunning with the helper-picked thread count.
-- **`thread_sweep.rs` mutates `MAGNOTIA_POWER_STATE_OVERRIDE` via `env::set_var`.** Globally process-wide. Concurrent tests in the same `cargo test` invocation that read `MAGNOTIA_POWER_STATE_OVERRIDE` will race. The test removes the var at the end (`thread_sweep.rs:94`).
+- **`thread_sweep.rs` mutates `LUMOTIA_POWER_STATE_OVERRIDE` via `env::set_var`.** Globally process-wide. Concurrent tests in the same `cargo test` invocation that read `LUMOTIA_POWER_STATE_OVERRIDE` will race. The test removes the var at the end (`thread_sweep.rs:94`).
 - **`tempfile 3` is a dev-dep, not a runtime dep.** Production code never creates temp files.
 - **`num_cpus = "1"` (the version, not "one CPU").** Test-only labelling; production uses the slice 5 helper.
 - **In-tree HTTP fixtures use ephemeral ports (`bind 127.0.0.1:0`) and run on a tokio task.** No port-collision risk, but a paranoid sandbox that blocks raw TCP loopback would break these tests.