Fix audit findings: path traversal, exec shell, glob dup, dead bread-sync, version drift

- modules_mgmt.rs: reject module names containing path separators, `..`,
  or absolute paths before joining onto modules_dir (install_from_local,
  remove_module, read_module_manifest); adds canonicalized containment
  check as defense in depth. Manifest-supplied names and CLI args were
  previously joined unsanitized, allowing path traversal on install/remove.
- breadd/src/lua/mod.rs: bread.exec now runs via `sh -c` instead of
  `sh -lc`; no documented reason was found for login-shell semantics.
- Unify the two independently hand-written glob matchers (subscription
  dispatch in breadd/src/core/subscriptions.rs vs. the CLI --filter path
  in breadd/src/ipc/mod.rs) into one implementation in
  bread-shared/src/glob.rs, used by both call sites.
- Remove the dead bread-sync/ tree (already excluded from the workspace
  and fully unreferenced) and its stale PKGBUILD deps (libgit2, git
  optdepend) and packaging docs mention.
- Correct the version-number transposition bug ("6.2.0" instead of
  "0.6.2"/"0.6.6") across bread-shared, breadd, and bread-cli Cargo.toml,
  and fix PKGBUILD's stale pkgver, so Cargo.toml/doctor/PKGBUILD all agree
  with the latest git tag (v0.6.6).

Cargo.toml

@@ -4,11 +4,6 @@ members = [
     "breadd",
     "bread-cli",
 ]
-# bread-sync is being extracted into its own project (see bread-sync/EXTRACTION.md).
-# Excluded so it no longer builds, tests, or gates CI as part of bread.
-exclude = [
-    "bread-sync",
-]
 resolver = "2"
 
 [workspace.dependencies]