Replace deploy scripts with self-contained compose bootstrap jobs

Removes every wrapper script under deploy/ (up.ps1, up.sh, scripts/*,
zitadel/provision.*) and folds their logic into three one-shot services
in compose.yml, following the pattern already used by seaweedfs-init:

  keys-init     generates the RS256 stream-ticket key pair
  migrate       applies the EF Core migrations (backend/Musify.Migrator.Dockerfile)
  zitadel-init  creates the Musify project + OIDC apps, writes the client
                ids back into the active env file

Deploying is now two plain `docker compose` commands, no scripts to run
or chmod:

  docker compose -f deploy/compose.yml -f deploy/compose.dev.yml up -d
  docker compose -f deploy/compose.yml -f deploy/compose.dev.yml --profile apps up -d --build

(swap compose.dev.yml for compose.prod.yml + --env-file deploy/.env.prod
for production). The first command brings up infra and lets the bootstrap
jobs run to completion; the second builds and starts the apps, which by
then read real OIDC values instead of empty ones — compose interpolates
${VAR} once per invocation, so this can't collapse into a single command
without the apps reading their own config file at container start instead
of via compose env (out of scope here).

Also:
- DatabaseDesignTimeFactory now also reads Database__ConnectionString
  from the environment, and DesignSettings.json is optional, so the new
  migrate container works without user-secrets or a config file excluded
  from the Docker build context by .dockerignore.
- nginx's depends_on no longer lists the apps-profile services: it does
  not need them at its own startup (every vhost resolves its upstream at
  request time via the embedded Docker resolver), and requiring them made
  `compose.prod.yml up -d` (without --profile apps) an invalid project.
- env_get/env_set in zitadel-init strip \r: the mounted env file can have
  CRLF line endings on Windows, which otherwise makes an empty-looking
  value non-empty to `[ -z ... ]`. .env.example/.env.prod.example are
  pinned to LF via .gitattributes for the same reason. Also fixed:
  rewriting the bind-mounted env file in place instead of renaming a temp
  file over it (rename onto a bind-mounted inode fails with "Resource
  busy").
- Removed compose.share.yml and zitadel/.output-share/ — a "temporary"
  personal overlay that had leaked a real Zitadel service-account PAT
  into git history (committed in 70968b3). That token should be rotated.
- Removed deploy/.tmp/ from .gitignore: nothing mounts or creates it
  anymore (it never actually did, either — no compose service referenced
  it, only the now-removed up.ps1 did).

Verified end-to-end with Docker: a clean `down -v` + fresh `up -d` +
`--profile apps up -d --build` on the dev stack brings up all four one-shot
jobs successfully and all four apps healthy (api/gateway return 200,
worker starts its consumers with no errors, web-player responds). Also
verified compose.prod.yml starts nginx cleanly with dummy certs and no
apps running, confirming the depends_on fix.

deploy/.env.example

@@ -1,5 +1,7 @@
 # Development configuration for deploy/compose.yml + compose.dev.yml.
-# Copy to deploy/.env (up.ps1 does it for you) and adjust. Not versioned.
+# Copy to deploy/.env and adjust. Not versioned.
+#
+#   cp deploy/.env.example deploy/.env
 
 DOTNET_ENVIRONMENT=Development
 
@@ -22,7 +24,7 @@ POSTGRES_HOST_PORT=59000
 # --- Zitadel (OIDC) ----------------------------------------------------------
 # The masterkey MUST be exactly 32 characters. The external domain/port form
 # the token issuer, so they have to match PUBLIC_AUTH_URL. Changing them needs
-# a re-init: ./up.ps1 -Destroy; ./up.ps1
+# a re-init: docker compose -f deploy/compose.yml -f deploy/compose.dev.yml down -v
 ZITADEL_MASTERKEY=MasterkeyNeedsToHave32Characters
 ZITADEL_EXTERNAL_DOMAIN=host.docker.internal
 ZITADEL_EXTERNAL_PORT=8080
@@ -31,8 +33,11 @@ ZITADEL_DATABASE_PASSWORD=zitadel
 # Console login: <username>@zitadel.<external domain>
 ZITADEL_ADMIN_USERNAME=admin
 ZITADEL_ADMIN_PASSWORD=Password1!
+# Allows the OIDC apps to use plain-http redirect URIs (dev only).
+ZITADEL_DEV_MODE=true
 
-# OIDC clients, filled in by deploy/zitadel/provision.ps1.
+# OIDC clients: the zitadel-init one-shot service (see compose.yml) fills
+# these in automatically on `docker compose up -d`.
 AUTH_CLIENT_ID=
 WEB_CLIENT_ID=
 WEB_CLIENT_SECRET=