Drop the canonical-containment 403 guard and the extra realpath(base) the
read routes (stat/read/raw/serve) had gained. Every workspace resolution
returns insideWorkspace: true and outside-file grants use
base = dirname(canonicalPath), so the guard could never fire; the flag had
no remaining reader and is gone with it. The read routes are back to the
single realpath(resolved.resolved) they had before.
Move the lexical-base fallback out of the inline header parsing in
routes.js. x-opencode-directory decoding belongs to
project-directory-runtime, so resolveProjectDirectory now also returns
requestedDirectory, the pre-realpath candidate that validated.
resolveWorkspacePathFromContext retries against it when the canonical base
rejects a path, which keeps files under a symlinked project root
addressable without a second copy of the header/query parsing.