fix: restore Android builds and adopt Signal v8.26.3

[purpleempress]

Summary

• Fix date-dependent patch retention: compare RFC author dates by instant instead of literal day padding.
• Rebase the full 24-patch Vesper feature series onto Signal Android v8.26.3, preserving original authors, dates, commit messages and sign-offs.
• Adapt the renamed navigation components/routes and toolbar APIs while retaining dynamic colours, profile-avatar menus and Vesper author badges.
• Preserve media-send theme application before Activity creation and the navbar's themed gesture inset; reuse upstream's existing resume hook.
• Add deterministic date regressions and supplemental post-materialisation source-contract checks.
• Keep the existing pull-request workflow/check names, restrict Blacksmith to trusted same-repository PRs, and upload an unsigned universal APK without signing/publishing.

Verification

• 41 patch-export tests pass. The fixed-date positive regression fails the original exporter and passes the repair.
• Both materialised-theme contract tests pass and were demonstrated failing before the corresponding repairs.
• All 24 patches apply to a fresh v8.26.3 materialisation; its tree exactly matches the exported source.
• Original author/date/message provenance and sign-offs verified for all 24 patches.
• Actionlint passes for every workflow; Python and embedded-shell syntax checks pass.
• Independent source review and workflow review completed; reported findings were corrected.
• Full local release assembly passed: :Signal-Android:assembleWebsiteProdRelease (16m 9s). The universal APK was checked with aapt: package systems.amber.vesper, version 8.26.3, versionCode 174701, all four ABIs.
• PR CI must pass before merge.

The source-contract tests supplement compilation, not on-device visual/lifecycle testing. Merging to main uses the existing signing and update-publication workflow.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-10T01:23:21.853357Z	8719373	PR opened

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