v2.80.0

Self-hosted ZenNotes server 2.80.0 with the pinned browser artifact web-2.80.0-web.hc6427fa53ec1c133 (built from ZenNotes/zennotes 31520814, the v2.80.0 release commit).

What changed for self-hosters:

• A vault keeps its template folder (ZenNotes/zennotes#1024). Desktop 2.80.0 can keep templates as ordinary notes in a folder of the vault (Settings, Templates, Template folder). The server keeps templates.folder in vault.json, normalized exactly as the desktop does, follows it through folder renames and moves, leaves the folder's checkboxes out of Tasks and its notes out of text search, and advertises supportsTemplateFolder, so a desktop or web app connected to this server offers the setting.
• Tasks name the checkbox they are a subtask of (ZenNotes/zennotes#1028). Each task carries a parentId, computed with the same rules as the desktop (a line that only continues a task's text keeps its subtasks under it) and held to the shared fixture, so the Kanban board folds subtasks into their card with a progress bar on a server vault too.
• The demo tour matches desktop 2.80.0, its numbered lists padded so 1 to 9 line up with 10.
• Kanban swimlanes (#1027), subtasks on the card (#1028), WIP limits (#1025), quieter Tasks views with one View menu and a Keys sheet (#1026, empty tasks out of the Calendar and Timeline panels and the home view too) and the template folder (#1024), in the web app as on desktop.
• Enter in a confirmation presses the focused button, Delete and Backspace delete database rows after asking, the Tasks calendar's Esc and a behave, and the rest of desktop 2.80.0's web-side fixes.

No Go dependency moved, so vendorHash stays.

Verification before publication: the release workflow (run 41128324951) built the five binaries from a481382 after go, docker and nix checks passed on #57; every binary matches SHA256SUMS, and the manifest.json asset is byte-identical to the pinned web-artifact/manifest.json (web-2.80.0-web.hc6427fa53ec1c133).

Docker: adibhanna/zennotes:2.80.0, 2.80 and latest are published from this tag by the repository's Docker publisher (linux/amd64 and linux/arm64, one digest).