refactor(build): unify release artifact zip names behind one source

[loss-and-quick]

Summary

Our release zip names had drifted apart, with the format hand-written in four places:

Artifact	Before
Android module	kasumi-proxy-vX.Y.Z.zip
Windows portable (release)	kasumi-proxy-X.Y.Z-windows-portable.zip
Linux portable (release)	kasumi-proxy-X.Y.Z-linux-portable.zip
Windows portable (nightly)	kasumi-proxy-X.Y.Z-portable.zip (no platform)

Inconsistencies: variant before the version for the module but after for the portables; v prefix kept for the module, stripped for the desktop builds; the nightly Windows portable missing its platform; and no Linux portable from the nightly at all.

This adds scripts/artifact-name.sh as the single source of truth (mirroring app-version.sh): given a variant it prints kasumi-proxy-<variant>-<version>.zip, version read verbatim from module.prop. Every producer now goes through it:

• package-release.sh — the Android module zip default (now kasumi-proxy-module-…)
• gen-update-json.sh — the Magisk/KernelSU updateJson zipUrl, which must match the uploaded asset. Renaming the module zip without this would point in-app updates at a 404 — the rename and this fix have to ship together.
• release.yml / nightly.yml — the portable-zip steps; the release module-upload step uses a build/*.zip glob so the workflow never re-states the name.

Also brings the nightly build in line: it now publishes a Linux portable zip (only Windows had one), and drops the dead BUILD_NAME env that package-release.sh never read.

Resulting names — one scheme, variant before version, v kept everywhere:

kasumi-proxy-module-vX.Y.Z.zip
kasumi-proxy-windows-portable-vX.Y.Z.zip
kasumi-proxy-linux-portable-vX.Y.Z.zip

Affected layer

• frontend/ — React Web UI
• crates/ · src-tauri/ — Rust core / backend / Tauri desktop
• module/ — Android installable zip (thin launcher over the Rust daemon)
• scripts/ — build / release helpers
• CI / .github/
• Docs only

Verification

• shellcheck clean on artifact-name.sh, package-release.sh, gen-update-json.sh
• actionlint (v1.7.12) clean on release.yml + nightly.yml (incl. its shellcheck pass over the edited run: blocks)
• artifact-name.sh {module,windows-portable,linux-portable} prints the expected names
• gen-update-json.sh regenerates update.json with zipUrl → kasumi-proxy-module-v0.4.1.zip (matches the uploaded asset); the version-specific update.json itself is left untouched (CI regenerates it on release)

Checklist

• Title is a scoped Conventional Commit; commits are logically split
• No build artifacts committed
• Generated frontend/src/generated/ not touched
• No user-visible strings changed
• Renames touching the project id were grepped in all case forms

Notes for reviewers

The Android module rename is the user-facing change; the gen-update-json.sh edit is the non-obvious half that keeps in-app updates working. update.json in the repo still references the old name — that file is regenerated and committed by the release workflow, so it self-corrects on the next release rather than being hand-edited here.