fix(media): TMDb's v3 key travels as a query parameter; Bearer is a JWT only

The first tvdb-grade TV plan built 49,771 moves with not ONE TMDb answer: every
search and every external_ids call came back 401. The credential on this box is
the v3 key (~/.config/secrets/tmdb, `api_key=`), and TMDb takes a v3 key only as
the `api_key` query parameter — a v4 request token is the only thing the Bearer
header accepts. Measured on the same credential in one pass: the query form
resolves `New Girl (2011)`, the Bearer form raises HTTP 401.

tmdb_request() now picks the transport from the shape it was handed (three
dot-separated segments = a JWT → Bearer, anything else → query parameter), and
the old header comment's reasoning is corrected: a token in argv is
world-readable in /proc/<pid>/cmdline, but this URL is built inside the process
and never reaches argv, so the query form leaks nothing.

The failure mode that let it look like a finished plan is fixed with it. The
401s were stderr-only, so the summary printed a confident move count while every
series folder still carried the metadata provider's folder-echo name — the exact
junk this contract exists to undo. Provider health is now part of the summary
line and of the exceptions file, and a test covers it offline with
`env -u TMDB_API_KEY`: a plan that asked and could not ask says NOT
provider-complete in both places, and still writes the moves it can justify,
because the answers that did arrive are worth their rename.

tests/media_shows.bats

@@ -135,6 +135,22 @@ plan_park() {                                  # the review pile outside the lib
         --park "$OUTSIDE" --out "$OUT" --exceptions "$EXC"
 }
 
+@test "--tmdb with no key is reported as an unfinished plan, not a finished one" {
+    # A dead provider is invisible where it happens: every 401 is one line on
+    # stderr, and a terminal that scrolled past them shows a plan that reads as
+    # complete while every folder still carries the metadata provider's junk. The
+    # plan is still written — the answers that DID arrive are worth their rename —
+    # so the state has to ride in the summary line and in the review file.
+    # env -u keeps this offline no matter what the developer's shell exports.
+    run env -u TMDB_API_KEY python3 "$PLAN" --root "$LIB" --enum "$ENUM" \
+        --titles "$TITLES" --probed "$PROBED" --tmdb-cache "$CACHE" \
+        --movies "$MOVIES" --tmdb --out "$OUT" --exceptions "$EXC"
+    [ "$status" -eq 0 ]
+    grep -q 'tmdb NOT ASKED (TMDB_API_KEY unset): NOT provider-complete' <<<"$output"
+    grep -q 'WARNING: tmdb NOT ASKED (TMDB_API_KEY unset) — NOT provider-complete' "$EXC"
+    grep -qE '^plan: [1-9][0-9]* moves' <<<"$output"
+}
+
 @test "the census exports the provider's episode numbering as a TSV" {
     DB="$BATS_TEST_TMPDIR/jellyfin.db"
     python3 - "$DB" "$SEASON" <<'PY'