Limit how much room people's files take

An anonymous person may keep 100 MB of images and sounds, an identified one
500 MB, and one person more by a file_allowance row the operator adds; all
of them together 15 GB, since every file is in the database and in each dump
the server keeps (decided 2026-10-02). Each comes from the environment
(FILE_LIMIT_*_MB), with these defaults, documented in deploy/.env.example.

The server checks when an upload starts, counting unfinished uploads so they
can't fill the disk unnoticed, and again when it finishes, counting what is
kept, so uploads started side by side can't overshoot; a refusal is a
FileLimitExceededException, and an upload refused as it finishes is deleted.
deletePerson deletes the allowance with the person. Migration: the new
table file_allowance, only added.

The app keeps a refused file waiting on the device and stops that round of
uploads; the Anki import warns when a deck's files may not fit in the room
left (asset.usage()).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

deploy/compose.yaml

@@ -53,6 +53,10 @@ services:
       SERVERPOD_PASSWORD_githubClientSecret: ${GITHUB_CLIENT_SECRET:-}
       # Where the source of what this instance runs is; empty: the project's.
       SOURCE_URL: ${SOURCE_URL:-}
+      # How much room people's files may take, in MiB; empty: the defaults.
+      FILE_LIMIT_ANONYMOUS_MB: ${FILE_LIMIT_ANONYMOUS_MB:-}
+      FILE_LIMIT_IDENTIFIED_MB: ${FILE_LIMIT_IDENTIFIED_MB:-}
+      FILE_LIMIT_INSTANCE_MB: ${FILE_LIMIT_INSTANCE_MB:-}
     depends_on:
       postgres:
         condition: service_healthy