fix(next): make computed relative chunk requires resolve in a compiled App Route - #8146

Merged rather than rebased: an earlier rebase of this branch silently
dropped five pushed commits, one of which (the landing-pad regression
revert, re-landed here as c133250) is load-bearing — without it a plain
try/catch aborts FATAL "no landing pad" under the default statepoint
build, because #7982 retypes every JS catch pad to a zero-action cleanup.

Conflict resolutions:

* crates/perry-hir/src/lower/expr_new.rs — main's `forward_class_shadows_local`
  (#8153) supersedes this branch's `is_current_class_self` gate on the callee
  snapshot. The depth rule keeps the mysql2 case working (a module-scope
  `class e` must not beat a factory-local `let e`) and is the form the branch's
  own class_self_new_shadowing tests are written against.
* crates/perry/src/commands/compile/cjs_wrap/wrap.rs — main's #8146 structure
  (explicit prefix test that STRIPS the leading `./`, `.json` fallthrough
  outside the block), plus this branch's bare `'.'` / `'..'` join. The latter
  is shipped behaviour the changeset claims: `js_require_path_module` resolves
  those through `directory_module_candidates`, and without the join the
  registry key stays a bare `.` and can never hit.
* crates/perry/src/commands/compile/build_cache.rs — both knobs kept.
  `PERRY_LL_RS4GC_OPTNONE_INSTRS` is already registered on main (#8128, with
  its own comment) and this branch listed it a second time; keeping main's
  line leaves both it and `PERRY_LL_O0_MAX_FN_BYTES` (#8144) registered
  exactly once each rather than duplicating one of them.
* crates/perry-codegen/src/codegen/entry.rs — comment-only divergence, main's.
* crates/perry/src/commands/compile/cjs_wrap/preamble_canary_tests.rs —
  `__perry_path_specifier` -> `__perry_path_spec` rename, main's.

Retargeted the two cjs_wrap tests that pinned this branch's pre-#8146
ternary form onto #8146's emitted shape.

…/server

With the abort gone, every request 500'd: Next opens .next/routes-manifest.json
relative to cwd, which does not exist under .next/server. The chunk-require
reason for that cwd is obsolete since #8146; the release fixture serves from
the package root and is the layout with production evidence.

…/server

With the abort gone, every request 500'd: Next opens .next/routes-manifest.json
relative to cwd, which does not exist under .next/server. The chunk-require
reason for that cwd is obsolete since #8146; the release fixture serves from
the package root and is the layout with production evidence.

…gate (#8205) (#8209)

* fix(test): C host + two-level namespace for the Next App Route dylib gate (#8205)

The gate aborted on its first request: the Rust provider-host exported rustc's
System-allocator shim, and the stdlib provider image was linked with
-flat_namespace, so its __rust_dealloc import bound to the host's shim while
the runtime image's shim is mimalloc. The first cross-image Vec drop in
js_node_http_server_process_pending freed a mimalloc pointer with libsystem
free() and aborted.

Replace provider-host.rs with a C host (same load order, flags, probe check
and event loop; no Rust allocator shim in the executable) and drop
-flat_namespace -interposable from provider-linker.sh so the stdlib image
binds its runtime imports two-level to libperry_runtime.dylib.

* changelog: fragment for #8209

* fix(test): serve the dylib gate host from the fixture root, not .next/server

With the abort gone, every request 500'd: Next opens .next/routes-manifest.json
relative to cwd, which does not exist under .next/server. The chunk-require
reason for that cwd is obsolete since #8146; the release fixture serves from
the package root and is the layout with production evidence.

* fix(test): exec the provider host so kill reaches it, not its subshell

Each cold start launched the host inside a (cd; host) & subshell and killed
the subshell pid; the host survived orphaned, kept serving, and held the port,
so a second cold start could never bind. Observed directly: a leaked
provider-host with ppid 1 still listening after the gate exited.

---------

Co-authored-by: Ralph Küpper <ralph@skelpo.com>