web: draw the chrome from sr-ht-ecore

The brand, the service switcher, the login block, the environment banner
and the database listing were a local port of core.sr.ht's nav — one of
five such ports on this instance, and they had already drifted. They are
now sourcecraft.dev/bigbes/sr-ht-ecore/chrome, the one copy every custom
service draws from.

Deleted: web/chrome.go entire (navEntry, networkOrder, networkExcluded,
buildNetwork, basePage, loginURL, logoutURL), templates/nav.html,
templates/icons/circle.svg (ecore inlines the identical SVG), the
repoList partial, and the local dict/shortHash duplicates.

Added: one chrome.Service built in newApp from our config section with
the hashed stylesheet href set on it, a chrome.Page per request through
app.page, chrome.Attach on every template set, and chrome.Funcs as the
base of the funcmap. Handlers embed chrome.Page in their view structs
instead of copying its fields; the row browser sets ContainerClass to
container-fluid, since its column count is the table's and not ours.

Three behaviour changes come with ecore's policy, all deliberate: the
profile link now prefers hub's ~username page when hub.sr.ht is
configured (it was always meta's /profile), the brand carries a fixed
15rem min-width so the switcher starts at the same x on every service,
and a binary built without a stylesheet renders bare rather than linking
an empty href. The nav test went with the code it tested — ordering,
exclusions and login URLs are ecore's to cover — and what replaced it
asserts only what is ours: that pages are drawn through the chrome at
all, and that the row browser is full-bleed.

The auth path is untouched: a foreign bearer token is still accepted as
a meta.sr.ht PAT.

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.