web: restyle dashboard and database lists after git.sr.ht

Replace the bare 'Your databases' heading and compact grid with the
git.sr.ht dashboard layout: a sidebar column with a welcome blurb plus
block buttons (create database, configure dolt credentials), and the
shared event-list cards for the database list. The repoList partial now
renders each database as an event card — name, visibility as small
muted text (non-public only, like git.sr.ht), description below — and
the profile page picks the same partial up automatically.

Adds a 'lower' template func for the visibility label and drops the now
unused .repo-list grid from main.scss (.event-list ships with the core
theme already).

feat(web): pluggable alternative-view registry for repositories

A repository can now expose specialized, read-only "views" chosen by the
shape of its tables, while the generic table browser stays available as a
fallback. A View fingerprints the tables (Applies), builds a model from
the browse layer (Build), and renders its own template; views register at
init time via RegisterView and are dispatched by slug at
/~user/db/view/{slug}. The overview shows a tab per applicable view.

The template loader parses each registered view's template with the
shared chrome, so a new view plugs in by adding two files (its .go with
init()+RegisterView and its .html) plus nothing else — no edits to the
registry, router, loader, or handlers. Build receives the request query
values so a view can offer sub-modes (e.g. a detail pane). No SQL engine
is involved; views read through the existing BrowseSession surface.

web: router, handlers, and sourcehut chrome

Chi route table per plan, SourceHut chrome port (nav/layout from
core.sr.ht Bootstrap structure), dual-flow clone box, dolt-key
association page with hash-fragment prefill, same-origin CSRF checks.
Handlers depend on small injected interfaces (StoreManager, RepoStore,
BrowseOpener, UserResolver) with production adapters included.