gitignore the in-repo git worktree directories

Agent worktrees are created under .worktrees/<branch> (and, in the older
repos of this family, .claude/worktrees/<branch>) so that they never
scatter as sibling directories next to the checkout. Neither path was
ignored here, so a worktree showed up as untracked in every git status
taken from the main checkout.

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.