rename: the server is Inkwell — package, env vars, image, compose, export marker

Step 2 of milestone 481. The operator chose a full rename (Scribe note 5071), so
this goes past the display strings into the identities:

- src/thoughtsync → src/inkwell; every import, the Dockerfile and both compose
  commands, alembic env, pyproject
- THOUGHTSYNC_* → INKWELL_* (database URL, secret key, log level, tag/port/bind)
- container data dir /var/thoughtsync → /var/inkwell
- image git.fabledsword.com/bvandeusen/inkwell; Postgres user/db default inkwell;
  CI's integration service follows
- the files the image serves are inkwell.*. fetch-clients.sh still fetches the
  thoughtsync-named release assets, because the lanes that publish them are
  renamed in steps 3 and 4
- exports are written with app "inkwell"

Two deliberate exceptions, both because data rides on them:

- compose volumes are now named explicitly and overridable (INKWELL_DB_VOLUME,
  INKWELL_DATA_VOLUME), so a deployment installed as ThoughtSync points at the
  volumes and DB identity it already has. .env.example says exactly what to set
- import still accepts app "thoughtsync", because exports written before the
  rename are backups. Tested both ways

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -20,7 +20,7 @@ RUN --mount=type=cache,target=/root/.cache/pip \
 # Bake the built SPA into the package's static dir (served by app.py). PYTHONPATH
 # points at /app/src so the runtime imports this source tree (with static/ present),
 # not the pip-installed copy.
-COPY --from=build-frontend /build/dist/ src/thoughtsync/static/
+COPY --from=build-frontend /build/dist/ src/inkwell/static/
 COPY alembic.ini .
 COPY alembic/ alembic/
 
@@ -41,7 +41,7 @@ COPY alembic/ alembic/
 # that step never ran. An image with no clients — or with some and not others — is
 # a supported state: the server advertises what it has and the web UI hides the
 # rest (client_dist.py).
-COPY client/ src/thoughtsync/client/
+COPY client/ src/inkwell/client/
 
 ENV PYTHONPATH=/app/src
 
@@ -52,4 +52,4 @@ EXPOSE 5000
 # Wait for the database, run migrations, then serve. The DB wait keeps a briefly
 # slow/unready database from crash-looping the container. Family convention
 # (rule 82): schema is built by real migrations, never metadata.create_all.
-CMD ["sh", "-c", "python -m thoughtsync.dbwait && alembic upgrade head && hypercorn 'thoughtsync.app:create_app()' --bind 0.0.0.0:5000 --keep-alive 600"]
+CMD ["sh", "-c", "python -m inkwell.dbwait && alembic upgrade head && hypercorn 'inkwell.app:create_app()' --bind 0.0.0.0:5000 --keep-alive 600"]