[Release] Documentation, regression gates, packaging, signing, and distribution readiness #15

Priority: P2 (release readiness, after core quality fixes)
Parent roadmap: #1

Goal

Ship a maintainable, reproducible Tuck build with an honest compatibility story. Personal ad-hoc builds should remain possible; public distribution may require Developer ID signing and notarization.

Deliverables

• Update README with supported macOS versions/architectures, how to install/uninstall, enable the Finder Sync extension, troubleshoot app URL-handler / helper IPC, and access Settings.
• Document available action categories, strict decimal-MB limits, non-destructive output naming, optional codec dependencies and known unsupported formats/features.
• Document dependency choices and associated third-party licenses/attributions; do not bundle or distribute third-party executables without complying with their licenses and signing constraints.
• Reproducible Swift 6 build and tests for Apple Silicon, with Intel support explicitly tested or documented as unsupported.
• Ensure optional encoders are discovered predictably (Homebrew/explicit paths) with helpful fallback errors; no silent install/download during use.
• Ensure build artifacts and large temp/caches go to verified external scratch locations for this developer's workflow; avoid deleting unrelated files, local worktrees or untracked backups.
• Separate headless unit/IPC/fixture tests from physical Finder/manual GUI verification. Maintain a release checklist for context menus, Settings, previews, permissions, collision handling, cancellation and original hashes.
• Assess signing/notarization path for future public distribution (entitlements, helper, Finder extension, bundled tools and updater). Do not require a paid Apple account for local personal installation.
• Review privacy/security story: local-only processing by default, secret/log redaction, file permissions, temporary-file cleanup, no unnecessary network calls, user confirmation for destructive operations.
• Define version numbering, changelog, release notes and artifact verification (checksums) without publishing anything automatically.

Acceptance criteria

• Fresh-machine installation steps are understandable and reproducible.
• Ad-hoc local installation works in ~/Applications.
• Optional encoder absence yields graceful degradation, not mysterious no-ops.
• Regression checklist covers current compression fixtures, PDF/image tools, metadata, ZIP, multi-selection and Finder helper IPC.
• Signing/notarization limitations for public distribution are explicitly documented and investigated.
• Release build instructions never implicitly push, tag, notarize or publish without approval.

Tests

Repeat installs, updates and uninstalls, user defaults persistence, Finder extension registration, code signature checks, both supported architectures if claimed, and manual GUI QA. Link any remaining blockers to individual issues instead of calling the release ready.