feat: auto-provision companion Dolt DBs from git.sr.ht pushes

Add a service-to-service path so pushing a git.sr.ht repo creates a matching
Dolt database at ~owner/name, ready before the user's first `dolt push`.

- web: POST /internal/repos, guarded by internal-IP + network-key `Internal`
  auth (not the browser cookie/CSRF). Resolves/mirrors the owner via
  auth.LookupUser, then CreateRepo + InitStore, rolling back the row if the
  store init fails. Idempotent: an existing companion returns 200, a fresh one
  201 — safe to call on every push.
- cmd/dolt-git-hook: the git.sr.ht post-update-script. Delegates every hook
  stage to the stock /usr/bin/git.sr.ht-update-hook unchanged (argv[0], stdin,
  env, exit code preserved; fail-closed if the delegate is missing), then on
  post-update POSTs the companion create and prints a one-time clone notice.
  Best-effort: never fails a push, degrades to a warning on any misconfig.

Tests cover the endpoint (provision/idempotent/rollback/bad-input) and the hook
(signed request round-trips through the guard's decryption, notice only on 201).

style(web): restyle the beads parade in the todo.sr.ht idiom

The board still read as a rounded-card kanban from another app. Re-skin
every surface in sourcehut's own issue-tracker language (todo.sr.ht):
flat and square — no border-radius, no shadows, no tints — hairline gray
borders, monospace ids, striped-on-hover rows instead of cards, and
squared bordered labels (the sourcehut .label: 1px border, no radius).
The summary becomes a flat hairline strip and each lane a squared column
with a 2px accent cap. The Mardi Gras hues survive only as small square
swatches and the lane cap, never as fills, so the view looks like a
native sourcehut tracker in both the light and dark themes. Verified via
a headless light/dark render. Test asserts the renamed summary class.

fix(web): make the beads view inherit the SourceHut theme

The beads board shipped its own Mardi Gras palette — a purple→green
marquee gradient and saturated solid lane fills — that clashed with
SourceHut's flat, utilitarian dark theme, and the detail pane's field
labels were a hardcoded dark purple with no dark-mode override, leaving
"Created by / Owner / Description" unreadable on the dark background.

Drive everything from CSS variables that mirror core.sr.ht's Bootstrap
palette for both the light default and the prefers-color-scheme: dark
variant sourcehut ships (the same media query it uses), so the view
inherits the host theme instead of fighting it. Lane hues become muted
Mardi Gras accents (gold/green/violet/gray) used only as thin borders and
low-alpha tints — never as body text — so contrast holds on either theme.
The marquee is now a flat stat row, lanes an understated panel with an
accent underline, and detail labels a readable muted caption. Verified
light and dark via a headless render.

feat(web): Mardi Gras beads view

Render a beads (bd) issue database as a Mardi Gras parade board: four
lanes — Rolling (in progress), Lined Up (open & ready), Stalled (open &
blocked), Past Stand (done) — plus a marquee of per-lane counts. Cards
show id/title/type/priority/assignee/labels and blocked-by/blocks counts;
an issue-detail pane (?issue=<id>) shows the full issue with its
dependency edges in both directions and its comments thread.

Fingerprints on the issues + dependencies tables and reads everything
through the browse layer (column-name-keyed, so column order is
irrelevant), capped at 2000 rows/table. Status is bucketed via
custom_statuses with name heuristics as a fallback; "blocked" means
is_blocked or an open blocking dependency. Plugs into the view registry
via init()+RegisterView with no framework edits. Purple/gold/green
palette scoped in the template (no scss rebuild needed).

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.

rename module to sourcecraft.dev/bigbes/sr-ht-dolt; depend on sourcecraft sr-ht-core

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.