RustBox 0.0.1 source release

Runtime/source model:
- one root Cargo package
- src/ Rust application code
- src/web/ RustBox-owned embedded browser UI
- migrations/ SQLite migrations
- no TypeScript/React/Next.js/Node.js/Bun build
- ManageSieve TLS/STARTTLS/explicit insecure transport option
- native systemd packaging

Oxi tracking:
- UPSTREAM_BASE stores consumed Oxi revision
- scripts/setup-upstream.sh configures upstream-oxi
- scripts/oxi-status.sh reports upstream changes
- scripts/sync-upstream.sh maps the cumulative Oxi backend delta into flat RustBox paths
- scripts/finish-upstream.sh advances UPSTREAM_BASE only after explicit upstream review/build validation
- scripts/oxi-port-commit.sh maps a selected Oxi backend commit without advancing the baseline
- Oxi frontend changes are reviewed and manually ported to src/web/
- docs/UI.md documents the browser UI/build conventions

Current 0.0.1 working snapshot additions:
- persisted special folders and mailbox behavior preferences
- bulk IMAP actions, copy/move, folder mark-all-read/empty, message-to-folder drag/drop
- HTML/plain/Markdown composer modes, CID inline images and expanded identity/signature rules
- advanced/saved search, tags, contact groups, visual Sieve/vacation builder
- IMAP IDLE/WebSocket refresh, desktop notifications and DND
- IMAP capabilities diagnostics and multi-account browser session UI
- RFC822 .eml download/import, List-Unsubscribe handling and RFC 8058 one-click HTTPS unsubscribe
- expanded contacts with multiple e-mails/phones/addresses, vCard profile fields, duplicate merge and validated PNG/JPEG/WebP photos
- calendar Month/Week/Day/Agenda views, richer event metadata and ICS import/export
- search-index status/rebuild, IMAP reconnect diagnostics and live cross-browser session revoke UI
- 31 contiguous SQLite migrations wired sequentially and executed on a fresh SQLite database during static validation
- safe Undo for resolvable IMAP MOVE actions and select-all across complete cached search results
- exact-token thread matching and expanded keyboard selection/navigation shortcuts
- in-app attachment preview, clipboard CID image paste and upload progress
- recoverable drafts with browser emergency snapshots and throttled IMAP Drafts snapshots
- outgoing priority and MDN/read-receipt draft/send options with pre-SMTP mailbox validation
- expanded Sieve visual rules: nested three-condition grouping, two actions, managed reordering, backup/restore, active overwrite guard and optional date-scheduled vacation
- spam destination default plus per-account override, pre-pagination flagged-first sorting with per-folder overrides, and subtle flagged-row markers
- direct ManageSieve quick-filter wizard with validation/save/activation and advanced-editor handoff
- unread browser/app badge updates and a public local-storage readiness endpoint
- inline image editing with display sizing, alignment, crop/cut preview and CID cleanup
- dedicated Composing settings for format, autosave interval, default priority, MDN and attachment reminder
- corrected Settings header/content grid for short panels and scroll-safe navigation

Validation note:
- JavaScript, JSON, TOML, SVG, shell syntax, UI selector/icon integrity and SQLite migrations were validated in the release environment.
- A full cargo build/test was not executed in this environment because cargo/rustc are not installed; run ./dev.sh or cargo test on a Rust toolchain host before deployment.