refactor(server): extract the version route into routers/version.py (R3) (#856)

GET /api/version + its exclusive _safe_http_url URL validator. Bodies verbatim
except @app -> @router and the VERSION-file lookup: Path(__file__).parent (the
app root when this lived at the top level) -> Path(__file__).resolve().parents[2]
(routers -> lib -> app root). VERSION ships at the app root in every packaging
path (Dockerfile COPY VERSION /app/, desktop bundle).

server.py: 7,275 -> 7,214.

Verified: pyflakes clean; route table IDENTICAL (143); pytest 2401 passed (33 in
test_version_endpoint, incl the URL-validation + env-override cases); eslint 0.
Boot smoke: /api/version returns the real version + validated source/license URLs.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server.py

@@ -55,7 +55,7 @@ from dlc_paths import _get_dlc_dir, _resolve_dlc_path
 # Lives in lib/ because that is the one core dir every packaging path copies.
 import appstate
 # Extracted route modules. They import `appstate`, never `server` — one-way graph.
-from routers import audio_effects, artist_aliases, loops, playlists, ws_highway, chart, wanted, library_extras, shop, progression, profile, stats
+from routers import audio_effects, artist_aliases, loops, playlists, ws_highway, chart, wanted, library_extras, shop, progression, profile, stats, version
 import sloppak as sloppak_mod
 import loosefolder as loosefolder_mod
 # Pure text-matching engine for MusicBrainz enrichment (P8): denoise/score/
@@ -3193,70 +3193,11 @@ def _periodic_rescan():
         time.sleep(300)
 
 
-def _safe_http_url(raw):
-    """Return `raw` stripped + trailing-slash-stripped if it parses as an
-    http(s) URL with a non-empty host; else None.
-
-    Used to validate operator-supplied `APP_SOURCE_URL` / `APP_LICENSE_URL`
-    env vars before they reach `<a href>` in the UI. A bare prefix check
-    like `startswith(("http://","https://"))` accepts malformed inputs
-    such as `"https://"` (no host) or `"https:///foo"` (empty host) that
-    still produce broken hrefs — and, when used as a base for the default
-    `license_url`, garbage like `"https:///blob/main/LICENSE"`.
-    """
-    from urllib.parse import urlsplit
-    if not raw:
-        return None
-    s = raw.strip().rstrip("/")
-    if not s:
-        return None
-    try:
-        parsed = urlsplit(s)
-    except ValueError:
-        return None
-    if parsed.scheme.lower() not in ("http", "https"):
-        return None
-    # `netloc` includes any `user:pass@` and `:port` — strings like
-    # "http://:80/path" have non-empty netloc (":80") but no real
-    # hostname. Validate `hostname` so only URLs with an actual host
-    # are accepted.
-    if not parsed.hostname:
-        return None
-    return s
 
 
-@app.get("/api/version")
-def get_version():
-    env_version = os.environ.get("APP_VERSION", "").strip()
-    if env_version:
-        version = env_version
-    else:
-        version_file = Path(__file__).parent / "VERSION"
-        version = "unknown"
-        if version_file.exists():
-            try:
-                version = version_file.read_text().strip()
-            except (OSError, UnicodeDecodeError):
-                pass
-    default_source_url = "https://github.com/got-feedback/feedBack"
-    # APP_SOURCE_URL / APP_LICENSE_URL flow straight into <a href> in the UI,
-    # so validate with urllib.parse rather than a bare prefix check — a prefix
-    # check accepts malformed values like "https://" (no host) which produce
-    # broken hrefs (and a constructed license_url like "https:///blob/main/LICENSE").
-    # _safe_http_url requires scheme in {http,https} AND a non-empty hostname
-    # (not just netloc — that would still accept port-only authorities like
-    # "http://:80/path"); fall back to the safe default otherwise.
-    source_url = _safe_http_url(os.environ.get("APP_SOURCE_URL")) or default_source_url
-    # APP_LICENSE_URL: explicit override for the LICENSE link. The default
-    # constructed value (source_url + "/blob/main/LICENSE") is GitHub-
-    # specific and assumes the repo's default branch is `main`; non-GitHub
-    # hosts (GitLab, Gitea, self-hosted) need an explicit value.
-    license_url = _safe_http_url(os.environ.get("APP_LICENSE_URL")) or (source_url + "/blob/main/LICENSE")
-    return {
-        "version": version,
-        "source_url": source_url,
-        "license_url": license_url,
-    }
+# ── App version / source URLs ────────────────────────────────────────────────
+# Mounted here (registration order). Implementation in lib/routers/version.py.
+app.include_router(version.router)
 
 
 @app.get("/api/scan-status")