feat: start the vss server for wallet backup tests

[ovitrif]

Description

• A vss compose profile starts the VSS server and its own database on port 5050 for wallet backup tests. The image builds on Debian bookworm.
• The review stack's test environment runs this change; the test run that needs it is reported in a comment here.
• Checked: The server answers GET /vss/getObject with HTTP 401 when no token is sent, and the lane check lists bitkit-docker:vss.

Out of Scope

• None.

[ovi-reviewer]

Suggestion: 👍 Approve

The test run on synonymdev/bitkit-android#1401 at head 98a1570 ran item 5, the one that needed the VSS server, on the environment built from commit d187ba3 of this change, and it passed.

Every item of the run that needed the change ran on it and passed, so the VSS server and its database started and served the wallet backup test as intended.

[ovitrif]

Validation: passes at 69d5ede. Ready to merge.

This PR conflicted with main in CHANGELOG.md only. I merged main in 69d5ede, keeping both changelog lines, and GitHub now reports it mergeable.

CI: the repository runs no checks on pull requests.

Local checks on 69d5ede:

• docker compose config resolves with no profile and with every profile.

Bring-up:

• I built the vss image from vss/Dockerfile with the pinned vss-server submodule (14d4b4f), on Debian bookworm, in 3 min 10 s.
• I started vss-postgres and vss in a Compose project of their own (Docker 29.4, arm64).
• vss-postgres turns healthy, and the server applies migrations 0 through 3 and listens on 5050.

Real calls:

• POST /vss/getObject without a token: 401.
• The repository's vss-test (vss_jwt_test):
  • listKeyVersions with an RS256 token signed by lnurl-server/keys/private.pem: 200.
  • The same call with a token from another key: 401.
  • Result: 2 passed, 0 failed.

The default stack's vss-server image no longer builds (vss-server/rust/Dockerfile installs libssl1.1, which the current Debian base does not ship). This profile's image is the one that builds.