Move the canonical forge to Codeberg (#86)

Makes Codeberg canonical for git, issues, PRs, tags and releases. The self-hosted Gitea instance stays build infrastructure: signing key, F-Droid publishing, release pipeline.

**This PR is its own test.** It is the first PR opened on Codeberg, so a green `CI` check proves the new runner works *and* that the submodule resolves from its new home.

### 1 · floret-kit moved

Mirrored to `jlmakiola/floret-kit` (6 branches, 3 tags, every SHA verified identical) and `.gitmodules` repointed. This is what actually unblocks contributors — a clone previously could not resolve its submodule without reaching the personal Gitea instance.

The Gitea copy is **kept**: every existing tag records the old submodule URL, so rebuilds of past releases (including F-Droid reproducible rebuilds) still resolve.

### 2 · Workflows split by directory

Forgejo's lookup is first-match-wins across `.forgejo/` → `.gitea/` → `.github/`, and Gitea cannot see `.forgejo/` at all. So each forge sees exactly one set, with no duplicated files and no expression to keep in sync:

| Directory | Runs on | Contains | Secrets |
| --- | --- | --- | --- |
| `.forgejo/workflows/` | Codeberg | `ci.yaml`, `translations.yaml` | **none** |
| `.gitea/workflows/` | Gitea | `release.yaml`, `renovate.yml` | all of them |

The line is drawn at **secrets, not CI-vs-release** — that is what makes fork PRs safe. Renovate deliberately does *not* move despite opening PRs here; it keeps running where its token already lives and merely talks to Codeberg's API.

### 3 · Two release-pipeline safety changes

- `release.yaml`'s `detect` gets an explicit `repository_owner` guard. The directory split only holds while `.forgejo/` is non-empty; empty it and Codeberg would fall back to `.gitea/` and start running the release pipeline on the contributor-facing runner, without secrets.
- `detect` now reads tags from **Codeberg**, not from the Gitea instance it runs on. Push mirroring is `git push --mirror`, so a tag minted on Gitea is deleted by the next sync until the Codeberg tag push propagates back — asking Gitea inside that window reports "no tag" for an already-shipped release and would cut it twice. It also now fails on any status other than 200/404 rather than reading a transient error as "no tag": a failed job is recoverable, a duplicate release is not.

### 4 · Links repointed

In-app Source/License links, README badge, both F-Droid metadata files. **`Repo:` in `docs/fdroid-official/` deliberately stays on Gitea** — it keeps receiving `main` and every tag, so it remains a complete build source, and leaving it alone means no fdroiddata MR and no reproducible-build risk.

### Not in this PR

Renovate + Weblate repointing, and the Codeberg → Gitea push mirror (browser-side).

Supersedes Gitea PR #104.

Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de>
Reviewed-on: https://codeberg.org/jlmakiola/calendula/pulls/86

.forgejo/workflows/translations.yaml

@@ -0,0 +1,39 @@
+name: Translations
+
+# Fast, SDK-free parity check for translation resources, so Weblate PRs (which
+# only touch values-*/strings.xml) get quick feedback without the full Android
+# build. The deeper checks still run in CI via lintDebug (ExtraTranslation).
+#
+# Runs on every PR (no path filter) so the required "Translations / check"
+# status is always reported — like the `ci` job. A path-filtered workflow is
+# skipped on unrelated PRs and never posts its status, which leaves that
+# required check pending forever and blocks the merge of any code-only PR into a
+# release/* branch. The check itself is cheap and simply passes when the
+# committed translations are consistent, so always running it costs nothing.
+on:
+  pull_request:
+
+concurrency:
+  group: translations-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    runs-on: docker
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Ensure python3
+        run: |
+          if ! command -v python3 >/dev/null 2>&1; then
+            if command -v apt-get >/dev/null 2>&1; then
+              apt-get update && apt-get install -y python3
+            elif command -v apk >/dev/null 2>&1; then
+              apk add --no-cache python3
+            fi
+          fi
+          python3 --version
+
+      - name: Check translation parity
+        run: python3 scripts/check_translations.py