Adopt template workflow conventions (release-asset, retention, docker-readme)

[ptr727]

Workflow portion of the template reconverge (follows #756, the docs portion). Aligns the GitHub Actions workflows with the current ptr727/ProjectTemplate conventions.

Changes

• Release-asset seam (Re-converge release workflows: collect GitHub-release assets via release-asset-<branch>-* convention #727): build-executable-task.yml now uploads the standalone build as release-asset-<branch>-executable and drops the artifact-id workflow output; build-release-task.yml's github-release job collects assets via pattern: release-asset-<branch>-* + merge-multiple instead of naming the build job. Same files land on the release; the orchestration stays reusable verbatim as targets change.
• Artifact retention (Re-sync from template #167: docs/comment cleanup, CI storage limits, new tasks #745): retention-days: 1 on the intermediate upload-artifact steps (the per-runtime publish-<branch>-<runtime>, the executable release asset, and versions-<branch>) so they no longer accrue against the 90-day account quota.
• Docker Hub readme: renamed build-dockerreadme-task.yml -> publish-docker-readme-task.yml and aligned the task/job names; kept PlexCleaner's m4 tool-version render and the working DOCKER_HUB_USERNAME / DOCKER_HUB_PASSWORD auth (the description-update endpoint needs a read/write/delete credential; the account password works, so it's retained rather than switched to a push-scoped token).
• Updated the AGENTS.md / ARCHITECTURE.md references to the renamed task.

Validation

Workflow-only changes are intentionally not path-filtered into PR smoke builds, so this is validated with actionlint locally (clean on all changed files) and a manual workflow_dispatch publish after merge (which exercises build-executable-task -> release-asset-* collection and the renamed docker-readme task end-to-end).

Closes #727. Closes #745.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR reconverges PlexCleaner’s GitHub Actions workflows with the current ptr727/ProjectTemplate conventions, focusing on the release-asset artifact seam, artifact-retention tuning, and the Docker Hub README publisher task rename.

Changes:

• Switch GitHub release assembly to the release-asset-<branch>-* artifact pattern (removing the prior per-job artifact-id wiring).
• Add retention-days: 1 to intermediate workflow artifacts to reduce long-lived artifact storage accumulation.
• Rename and rewire the Docker Hub README reusable workflow to publish-docker-readme-task.yml, updating references accordingly.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
ARCHITECTURE.md	Updates the workflow/task inventory to reflect the Docker README task rename.
AGENTS.md	Updates documentation references to the renamed Docker README task and reflects the release-asset seam wording.
.github/workflows/publish-release.yml	Points the release publisher to the renamed Docker README reusable workflow and updates the job name.
.github/workflows/publish-docker-readme-task.yml	Renames the reusable workflow and job labels to match the template naming conventions.
.github/workflows/build-toolversions-task.yml	Adds retention-days: 1 to uploaded versions artifacts and updates the consumer reference comment.
.github/workflows/build-release-task.yml	Downloads release assets via pattern: release-asset-<branch>-* + merge-multiple instead of artifact-ids.
.github/workflows/build-executable-task.yml	Removes the reusable-workflow artifact-id output, uploads the executable as release-asset-<branch>-executable, and sets artifact retention to 1 day.