Add zip upload and mapped-path picker for outline import

Sandbox source paths under a configured Imports:RootPath, browse it
from the web dialog, upload a zip that extracts into staging, and
import a single markdown file (agent infers chapter vs character).

CLAUDE.md

@@ -103,5 +103,6 @@ Several real bugs here — SQLite refusing ORDER BY DateTimeOffset, agent's mode
 - Anthropic model id lives in `appsettings.json` under `Agent:Model`. Don't hardcode.
 - API key comes from `ANTHROPIC_API_KEY` or `Agent:ApiKey` — never commit one. App must stay fully usable without key; only agent endpoints require it.
 - EF migrations: `dotnet ef migrations add <Name> -p src/Novelly.Api -o Data/Migrations`. API migrates on boot.
+- Outline import root lives in `appsettings.json` under `Imports:RootPath` (`Imports__RootPath` env var). When set, it's the only folder the browse/upload import endpoints and the source picker can reach; unset, those endpoints are disabled and the dialog falls back to a typed path with no sandbox. Created at boot if missing.
 - `git push` runs `scripts/ci/prepush.sh` through Husky: build, test, then web build. Run `npm install`
   once at repo root to install hook.