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>

.env.example

@@ -1,4 +1,4 @@
-# ThoughtSync production settings. Copy to `.env` and edit:
+# Inkwell production settings. Copy to `.env` and edit:
 #
 #   cp .env.example .env
 #
@@ -29,15 +29,15 @@ POSTGRES_PASSWORD=
 #
 # NOTE: `main` can sit well behind `dev`. If a feature you expect is missing,
 # check which branch it actually landed on before assuming a bug.
-#THOUGHTSYNC_TAG=latest
+#INKWELL_TAG=latest
 
 # The host port the app is published on.
-#THOUGHTSYNC_PORT=5000
+#INKWELL_PORT=5000
 
 # Which interface to bind. The default (all interfaces) is what lets desktop
 # clients on your network reach the server. Behind a reverse proxy, set this to
 # 127.0.0.1 so only the proxy can talk to it.
-#THOUGHTSYNC_BIND=0.0.0.0
+#INKWELL_BIND=0.0.0.0
 
 # NOTE: how many proxies sit in front of this app is a SETTING, not an env var —
 # Settings → Security → "Trusted proxy hops" in the admin UI. It defaults to 1 (one
@@ -47,12 +47,31 @@ POSTGRES_PASSWORD=
 # How much the app says. Credential events (sign-ins, failures, throttles, new
 # accounts, device tokens issued) are logged at INFO and read with
 # `docker compose logs app`.
-#THOUGHTSYNC_LOG_LEVEL=INFO
+#INKWELL_LOG_LEVEL=INFO
 
 # Database identity. Changing these AFTER the first start does not rename anything
 # that already exists — the volume keeps whatever the first run created.
+#POSTGRES_USER=inkwell
+#POSTGRES_DB=inkwell
+
+# --- Upgrading from ThoughtSync ---------------------------------------------
+#
+# Inkwell was called ThoughtSync, and a deployment installed under that name has
+# its data in volumes and a database named for it. Point at them instead of
+# renaming anything. Leaving these unset on such a deployment starts Inkwell
+# against EMPTY volumes; the old data is untouched, but you would not see it.
+#
+# Use the full names `docker volume ls` prints — compose prefixes them with the
+# project name, so they usually look like `thoughtsync_thoughtsync-db`:
+#INKWELL_DB_VOLUME=thoughtsync_thoughtsync-db
+#INKWELL_DATA_VOLUME=thoughtsync_thoughtsync-data
+#
+# And the database identity the first start created, which a volume keeps:
 #POSTGRES_USER=thoughtsync
 #POSTGRES_DB=thoughtsync
+#
+# Rename any THOUGHTSYNC_* lines already in your .env to INKWELL_* — the old
+# names are no longer read.
 
 # --- a note on HTTPS --------------------------------------------------------
 #