docs: update AGENTS.md with current commands and features

- Add web-deps, nidusctl, and migrate commands to build section
- Document ICS/webcal subscriptions and Birthdays calendar
- Note Migrate() is idempotent
- Add additional database tables
- Include Docker/CI and database migration details

AGENTS.md

@@ -9,16 +9,18 @@ collections. A small server-rendered web UI (templ + Tailwind + htmx) at
 ## Build, test, lint
 
 ```bash
-make build          # go build -o bin/davserver ./cmd/server
+make build          # go build -o bin/davserver ./cmd/server + ./bin/nidusctl
 make run             # build + ./bin/davserver -config config.yaml
 make test            # go test ./... -v -race
-make lint            # golangci-lint run ./...
+make lint            # golangci-lint run ./... (no config file; uses defaults)
 make tidy            # go mod tidy
-go test ./internal/store/ -run TestStoreRoundTrip -v   # single test
+make web-deps        # install Tailwind CLI + TypeScript (needed once, or after web/package.json changes)
 make templ-generate  # regenerate *_templ.go after editing internal/web/templates/*.templ
-make web-css         # templ-generate + rebuild web/static/app.css (needs `make web-deps` once, Node.js/npm)
+make web-css         # templ-generate + rebuild web/static/app.css
 make web-ts          # compile web/ts/*.ts to web/static/*.js
 make web-assets      # web-css + web-ts (everything under web/static/)
+make nidusctl        # build + run nidusctl with ARGS (e.g. `make nidusctl ARGS="user list"`)
+go run ./tools/migrate -config config.yaml  # restructure data directory
 ```
 
 Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
@@ -51,14 +53,15 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
   if it's nil. `auth.NewContext(ctx, p)` is the test-only inverse, used to
   build authenticated contexts without a real Basic Auth handshake.
 - `internal/store` — the single source of truth for all persisted data.
-  A thin filesystem KV abstraction: `<data_dir>/<user>/<collection>/<objectID>`.
+  A thin filesystem KV abstraction: `<data_dir>/<user>/[calendars|addressbooks|files]/<name>`.
   All collection/object names pass through `sanitize()` (via
   `filepath.Base` + strip `..`) to prevent path traversal — preserve this
   when adding new store methods. Writes use temp-file + rename for atomicity
   (`PutObject`). Locking is sharded per-user (`lockFor(user)`, a
   `map[string]*sync.RWMutex` guarded by its own mutex) rather than one
   global lock, so different users' requests don't serialize against each
-  other.
+  other. `Migrate()` restructures data from the old format (`cal-<name>`,
+  `card-<name>`) to the new unified layout and is idempotent.
 - `internal/caldav` and `internal/carddav` — implement the
   `caldav.Backend`/`carddav.Backend` interfaces from `github.com/emersion/go-webdav`
   on top of `store.Store`. Calendars are stored as collections prefixed
@@ -100,6 +103,12 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
   shared data is never copied — it's read/written directly under the
   owner's own `store.Store` namespace, just addressed via the synthetic
   name from the grantee's requests.
+  **ICSSubscriptions**: read-only calendars backed by remote ICS/webcal
+  URLs (see `db.CreateICSSubscription`, `internal/db/ics.go`) are exposed
+  alongside real calendars under `/cal/home/<name>/` (shared namespace;
+  see `internal/caldav/ics.go`). `Birthdays` is a computed calendar
+  synthesized from contacts' BDAY fields (see `internal/caldav/birthdays.go`,
+  `internal/birthdays/birthdays.go`).
 - `internal/db` — a small `database/sql` wrapper around
   `modernc.org/sqlite` (pure Go, no CGO) at `<data_dir>/nidus.db`. Only
   one open connection is used (`SetMaxOpenConns(1)`) since SQLite allows a
@@ -118,6 +127,9 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
   cleans those up in a transaction. `modernc.org/sqlite` has no typed
   unique-constraint error, so `isUniqueConstraintErr()` string-matches the
   driver's error message.
+  **Additional tables**: `birthday_calendars` (per-user display color for
+  the computed Birthdays calendar), `ics_subscriptions` (remote ICS/webcal
+  calendar subscriptions), `web_sessions` (server-side session tokens).
 - `internal/webdav` — plain-file WebDAV via `golang.org/x/net/webdav`,
   mounted at the single fixed URL `/files/` for all users (no username in
   the path either). `NewHandler` caches one `*xwebdav.Handler` per
@@ -128,6 +140,10 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
 - `tools/hashpwd` — standalone CLI (`go run ./tools/hashpwd <password>`) to
   generate bcrypt hashes for ad-hoc testing (no longer needed for normal
   user setup — see `nidusctl user create` below).
+- `tools/migrate` — restructures data directory from old format (`cal-<name>`,
+  `card-<name>`) to unified layout (`calendars/`, `addressbooks/`,
+  `files/`). Run automatically on server startup; invoke manually with
+  `go run ./tools/migrate -config config.yaml`.
 - `tools/nidusctl` — standalone admin CLI (`go run ./tools/nidusctl
   -config config.yaml <user|calendar|addressbook> ...`) — the only way to
   create/delete users, calendars, and address books, plus manage sharing
@@ -190,6 +206,14 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
   no runtime dependency on Node.js or the `web/` directory being present —
   Node/npm are only needed when actually changing templates/styles/TS
   (`make web-assets` rebuilds everything under `web/static/`).
+  **Web UI features**: dashboard (calendars/address books/ICS subscriptions
+  management), login (cookie-based sessions), share management (create/update/
+  revoke share grants via htmx), files browser (inline preview, upload, download),
+  contacts manager (vCard import/export, edit fields), calendar view (month/week,
+  per-calendar colors), account settings (name/email/password). The
+  synthetic `Birthdays` calendar (computed from contacts' BDAY fields) and
+  ICS/webcal subscriptions are managed via the web UI just like real
+  calendars.
 
 ## Conventions
 
@@ -211,3 +235,5 @@ Test files: `internal/store/store_test.go`, `internal/webdav/handler_test.go`,
 - Logging uses `log/slog` structured fields (e.g. `logger.Warn("...", "user", u, "error", err)`), passed down explicitly to every constructor (`NewBackend`, `NewHandler`, `NewMiddleware`) rather than a global logger.
 - Config module path is `github.com/yourusername/caldav-server` (go.mod name
   predates the `nidus` repo rename) — import paths still use this, not `nidus`.
+- **Docker/CI**: Docker image pushed to `git.arnef.de/arnef/nidus` on tags (`v*`) or releases (`.github/workflows/docker-release.yml`), multi-arch (`linux/amd64`, `linux/arm64`). Use `docker-compose` for local dev with healthcheck on `/healthz`.
+- **Database schema** lives in `internal/db/db.go` `migrate()` — all tables are created with `CREATE TABLE IF NOT EXISTS` and schema changes are applied via `ALTER TABLE` in `migrateAddColumns()`. No external migration framework.