Backport official GLib iterator safety fix for Linux desktop

tools/glib-regression/README.md

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+# Optimized GLib backport regression
+
+Run on native Linux with the GLib development headers and the normal Rust
+toolchain. This isolated harness selects searchi's exact vendored GLib crate.
+
+Before building, verify all upstream bytes and the exact patch against the
+official crate archive already available in the Cargo download cache:
+
+```sh
+python tools/glib-regression/verify_vendor.py /path/to/glib-0.18.5.crate
+```
+
+This reads the archive without extracting it or changing the Cargo cache and
+rejects extra, missing or unexpectedly changed vendor files.
+
+```sh
+cargo test --manifest-path tools/glib-regression/Cargo.toml --release --locked --jobs 1
+```
+
+The release profile is essential: the upstream defect was sensitive to compiler
+optimization. Tests exercise all five affected iterator operations, Unicode,
+empty arrays, exhaustion and exact-size behavior. A compile-fail doctest verifies
+borrowed strings cannot outlive their owning variant. No embeddings, media
+decoders, network inference or GPU providers are used.
+
+This harness does not replace a native desktop build/interaction check or an
+advisory audit. Record actual execution and selected package identity before
+calling the local backport validated.