chore: move business tooling out of the public library; tidy filestore naming

Keep the public tree project-generic. Business/one-off tools, deployment
and business docs move to the private oo-workspace repo.

Moved to oo-workspace:
- cmd/ooscan, cmd/pdfamount, cmd/kontoblatt, cmd/kontolink
- internal/xlspipe (cutover-portugal workbook) -> oow workbook build
  (drops the --template/--title flags from oo docs put-xlsx)
- deploy/docker-compose.rclone-webdav.yml + docs/rclone-webdav.md
- docs/crm-associations.md

Removed GitHub-era leftovers:
- .github/workflows/release-please.yml, release-please-config.json,
  .release-please-manifest.json (tags are created on Gitea per SemVer)

Naming: the FileStore subsystem is now filestore_*.go (was file_*.go) to
match files_*.go (project Documents). Docs/AGENTS/README updated.

.github/workflows/release.yml

@@ -20,8 +20,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       # Always clone default branch first. workflow_dispatch often races with
-      # release-please creating the tag; fetching refs/tags/X before it exists
-      # fails checkout. Retry fetch, then check out the tag.
+      # tag creation; fetching refs/tags/X before it exists fails checkout.
+      # Retry fetch, then check out the tag.
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0