fix(build): move appstate.py + routers/ under lib/ so the desktop app ships them (#836)

The packaged desktop app died at startup:

    File ".../Resources/slopsmith/server.py", line 71, in <module>
        import appstate
    ModuleNotFoundError: No module named 'appstate'

feedback-desktop's scripts/bundle-slopsmith.sh copies a HARDCODED list of core
files into the bundle -- server.py, VERSION, lib/, data/, static/,
plugins/__init__.py. The root-level appstate.py (#833) and routers/ (#834)
shipped fine in Docker, passed every test, and were silently dropped from the
packaged app.

Both now live under lib/, the one core directory every packaging path already
copies wholesale -- Dockerfile `COPY lib/`, docker-compose.yml, and the desktop
bundler's `cp -r lib` -- and that all three put on sys.path (on Windows via the
embeddable-Python ._pth, where PYTHONPATH is ignored: build-windows.sh writes
`../slopsmith` and `../slopsmith/lib`). No feedback-desktop change and no new
release are needed for this to take effect.

lib/ is also the CORRECT home under Principle V, and always was once the design
settled: with the injection seam, appstate.py constructs nothing and does no
import-time IO, and a route module only builds an APIRouter. The premise that
forced root placement -- "appstate opens sqlite at import" -- stopped being true
when configure() replaced ownership. The Dockerfile / .dockerignore /
docker-compose.yml entries added for the root layout are reverted; nothing else
in core changes (git mv, so --follow survives).

tests/test_packaging.py is the guard: it walks server.py's module-level imports,
keeps the ones resolving inside this repo, and fails if any lives outside a
directory the packagers copy -- with the ModuleNotFoundError spelled out. So the
next root-level core module can't ship broken. Negative-checked: restoring
appstate.py to the root fails it; the message names the file and the four
packaging files a root module would have to teach.
(It also has to skip `origin in {"built-in","frozen"}` -- on 3.14 the frozen
stdlib reports origin="frozen", and Path("frozen").resolve() lands inside the
repo, which flagged `os` and `stat` as first-party.)

Verified: the bundler's copy replicated exactly into a temp dir and booted with
PYTHONPATH=<bundle>:<bundle>/lib -- `import server`, `import appstate`,
`import routers.audio_effects` all resolve, appstate.meta_db is server.meta_db,
143 routes. The same simulation against origin/main reproduces the production
ModuleNotFoundError. pytest 2398 passed (2348 + 50 new); route table still
identical to origin/main (paths, methods, order); docker build context reaches
lib/appstate.py and lib/routers/ with no __pycache__; native uvicorn boot smoke
serves /api/version, /api/library, the moved audio-effects router, and all three
migrated plugins' src/ graphs; eslint 0 errors.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server.py

@@ -68,6 +68,7 @@ from metadata_db import (
 from audio_effects_db import AudioEffectsMappingDB
 # The router seam. Imported as a module (never `from appstate import ...`) so
 # `appstate.configure(...)` below publishes into the same namespace routers read.
+# Lives in lib/ because that is the one core dir every packaging path copies.
 import appstate
 # Extracted route modules. They import `appstate`, never `server` — one-way graph.
 from routers import audio_effects