## Why
Clients running an app-server on one OS and an exec-server on another OS
need to be able to pass sandbox config to app-server that refers to
resources on the executor's foreign OS.
## What
`AbsolutePathBuf` can't represent these paths and we don't want users to
be exposed to `PathUri` yet, so this moves the public app-server API to
be expressed in terms of `ApiPathString`.
Stacked on #28165.
- change app-server v2 filesystem permission paths, including legacy
read/write roots, to `ApiPathString`
- localize API paths through `PathUri` when converting into the current
native core permission types
- make path-bearing permission conversions fallible and surface
localization failures instead of silently treating malformed grants as
ordinary denials
- propagate conversion failures through app-server and TUI approval
handling
- regenerate the app-server JSON and TypeScript schemas
- leave migration TODOs on native-path conversions so they can be
removed once core permission paths use `PathUri`
## Why
We're moving to `PathUri` in more places to support cross-OS
app-server/exec-server, but we don't want to expose the URI encoding to
users of app-server's public APIs yet.
We'll need to translate at the app-server API boundary between
client-visible "regular" paths that are appropriate for the OS of the
environment for which the paths make sense, which means using the
environment's path personality to do the conversion.
`PathUri` doesn't yet attempt to encode environment ID, so for now we'll
sniff the most likely path convention for a given path.
## What
- Add `PathConvention` and `NativePathString` with host-independent
POSIX, Windows drive, and UNC rendering.
- Cover cross-host rendering, encoding, Unicode, invalid components.
Adam Perry @ OpenAI