* fix: preserve redaction and state across incomplete updates

Fix credential truncation, omitted-window notification state, pending history-range synchronization, and failed provider-list handling. Add Qt and page-handler regressions. Documentation: update usage/development guides and Unreleased; no parity TODO or CLI contract changes. Verification: make check and focused tests pass with documented local KDE/actionlint/pyflakes skips.

* fix: preserve loader syntax through credential filtering

Address the Codex review: filter original warning syntax in bounded source and lookahead windows, then redact the retained result. Test long credential-like paths and warning-only fallback. Documentation: refine the Unreleased security entry; other guides and TODO remain accurate. Verification: make check passes with the documented local skips; the added regression fails on the previous commit.