Add bread-utils and bread-onnx: shared crates for ecosystem-wide duplication

bread-utils extracts genuinely duplicated logic found across breadbox,
breadclip, breadmon, breadcrumbs, bos-settings, and breadhelp:

- hypr: Hyprland socket1 request/response client (breadbox's
  get_active_workspace + breadclip's position.rs hyprctl_json were
  near-identical), socket2 path resolution (breadmon), and a
  version-tolerant `fullscreen` field parser (Hyprland has shipped both
  bool and int representations across versions).
- singleton: correct flock-based single-instance toggle, replacing the
  TOCTOU-prone read-pid/check-proc/kill/write-pid pattern duplicated
  verbatim between breadbox and breadclip (breadclip's own comment says
  "matches breadbox pattern").
- proc: breadcrumbs' timeout-guarded subprocess runner, promoted verbatim
  as the one implementation in the ecosystem that already got this right.
- atomic + xdg: atomic (temp-then-rename) file writes with an optional
  .bak-before-overwrite variant, and XDG path helpers that never fall back
  to a literal "~/..." string (the exact breadclip-core and
  breadpad-shared bug: PathBuf never expands `~`).
- tomlcfg (feature "toml"): the load_doc/save_doc TOML-editing discipline
  bos-settings and breadhelp both implemented byte-for-byte identically in
  the same fix pass that introduced it.
- gtk_popup (feature "gtk"): layer-shell overlay window setup, visible-row
  navigation, and click-outside-close, deduplicated from breadbox and
  breadclip (~150 duplicated lines, per both apps' own "same as breadbox"
  comments).

bread-onnx extracts the embedding pipeline (tokenize -> tensor build ->
mean-pool -> L2-normalize) duplicated near-verbatim between breadarr and
breadsearch, a shared execution-provider session builder with loud EP-
registration logging, and a model download+integrity helper. Defaults AMD
iGPU acceleration to ort::ep::MIGraphX (not ROCm) per this machine's own
breadsearch-gpu-backends lesson: ROCMExecutionProvider silently no-ops to
CPU on distro ROCm onnxruntime builds compiled with --use_migraphx.

Both crates build and pass their own test suites standalone. Consumer
migrations follow in subsequent commits.

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["bakery", "bread-theme"]
+members = ["bakery", "bread-theme", "bread-utils", "bread-onnx"]
 resolver = "2"
 
 [workspace.package]
@@ -20,6 +20,7 @@ hex = "0.4"
 clap = { version = "4", features = ["derive", "env"] }
 chrono = "0.4"
 minisign-verify = "0.2"
+tracing = "0.1"
 
 [profile.release]
 lto = "thin"