feat(2-E.5): single-source-of-truth stream registry

Eliminates the duplication that has been hand-bumped through PRs B, C, D, E.
Adding a stream is now one StreamEntry in src/central/streams.py + one
migration row in config.streams. supervisor STREAM_SUBJECTS / archive
STREAMS / gui DASHBOARD_STREAMS all derive at import time. No drift
possible because there is one source.

Pure refactor; no behavior change. Runtime verified: derived structures
are byte-equivalent to the previous literal definitions.

src/central/streams.py (new):
  @dataclass(frozen=True)
  class StreamEntry:
      name: str
      subject_filter: str
      event_bearing: bool = True   # archive consumes from this stream
      dashboard: bool = True       # GUI dashboard surfaces this stream

  STREAMS: list[StreamEntry] = [
      StreamEntry("CENTRAL_WX",       "central.wx.>"),
      StreamEntry("CENTRAL_FIRE",     "central.fire.>"),
      StreamEntry("CENTRAL_QUAKE",    "central.quake.>"),
      StreamEntry("CENTRAL_SPACE",    "central.space.>"),
      StreamEntry("CENTRAL_DISASTER", "central.disaster.>"),
      StreamEntry("CENTRAL_META",     "central.meta.>", event_bearing=False),
  ]

Consumers derive:
  supervisor.STREAM_SUBJECTS = {s.name: [s.subject_filter] for s in STREAMS}
    (includes META: supervisor must create every stream in JetStream)
  archive.STREAMS = [(s.name, s.subject_filter) for s in STREAMS if s.event_bearing]
    (excludes META: status messages, not events)
  gui.DASHBOARD_STREAMS = [s.name for s in STREAMS if s.dashboard]

To resolve the name collision between the registry STREAMS and the
existing archive.STREAMS public symbol, archive.py imports the registry
under an alias: from central.streams import STREAMS as STREAM_REGISTRY.
The archives STREAMS surface (the tuple-list) is unchanged for callers.
Same alias used in supervisor.py and gui/routes.py for symmetry.

Migration files unchanged. config.streams keeps seeding retention/bytes --
operator-tunable ops state, separate SoT from the structural mapping.

Tests:
  Dropped from test_archive_multi_stream.py (7, all tautological vs. registry):
    test_streams_list_has_five_entries (magic-number count)
    test_streams_contains_central_wx / fire / quake / space / disaster
    test_streams_excludes_central_meta
  Dropped from test_dashboard.py:
    `assert len(streams) == 6` line inside test_single_stream_failure_doesnt_crash_card
    (the test itself stays; only the magic-number assertion is removed)
  Added in test_stream_registry.py (8 invariant tests):
    test_stream_names_unique
    test_subject_filters_unique
    test_subject_filter_central_prefix_wildcard
    test_meta_is_only_non_event_bearing
    test_supervisor_stream_subjects_includes_meta
    test_supervisor_stream_subjects_includes_all
    test_archive_streams_excludes_non_event_bearing
    test_dashboard_streams_matches_dashboard_flag

The new tests assert properties (uniqueness, format, derivation correctness),
not literals. Future stream additions need zero new test code -- every
invariant automatically covers them.

Note: test file named tests/test_stream_registry.py (not test_streams.py)
to avoid colliding with the pre-existing tests/test_streams.py, which
covers the GUI streams-management page.

Full suite: 427 passed (was 426 on main: -7 dropped + 8 added).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_stream_registry.py

@@ -0,0 +1,80 @@
+"""Registry-consistency tests for src/central/streams.py.
+
+These are property tests, not literal restatements. Adding a new stream to the
+registry requires no new test code -- every invariant here automatically
+covers it.
+"""
+
+import re
+
+from central.streams import STREAMS
+
+
+def test_stream_names_unique():
+    names = [s.name for s in STREAMS]
+    assert len(names) == len(set(names)), "duplicate stream names in registry"
+
+
+def test_subject_filters_unique():
+    filters = [s.subject_filter for s in STREAMS]
+    assert len(filters) == len(set(filters)), "duplicate subject filters in registry"
+
+
+def test_subject_filter_central_prefix_wildcard():
+    pattern = re.compile(r"^central\.[a-z][a-z_]*\.>$")
+    for s in STREAMS:
+        assert pattern.match(s.subject_filter), (
+            f"{s.name}: subject_filter {s.subject_filter!r} does not match /^central\\.[a-z][a-z_]*\\.>$/"
+        )
+
+
+def test_meta_is_only_non_event_bearing():
+    """CENTRAL_META is the only non-event-bearing stream today.
+
+    If you're adding a second one, update this test deliberately -- the
+    archive will silently skip the new stream, which is rarely what you want.
+    """
+    non_event = [s for s in STREAMS if not s.event_bearing]
+    assert len(non_event) == 1, (
+        f"expected exactly one non-event-bearing stream, got {[s.name for s in non_event]}"
+    )
+    assert non_event[0].name == "CENTRAL_META"
+
+
+def test_supervisor_stream_subjects_includes_meta():
+    """Supervisor creates every stream in JetStream, including META."""
+    from central.supervisor import STREAM_SUBJECTS
+
+    assert "CENTRAL_META" in STREAM_SUBJECTS
+    assert STREAM_SUBJECTS["CENTRAL_META"] == ["central.meta.>"]
+
+
+def test_supervisor_stream_subjects_includes_all():
+    """Every registry stream appears in supervisor's derived dict with the right filter."""
+    from central.supervisor import STREAM_SUBJECTS
+
+    assert set(STREAM_SUBJECTS.keys()) == {s.name for s in STREAMS}
+    for s in STREAMS:
+        assert STREAM_SUBJECTS[s.name] == [s.subject_filter]
+
+
+def test_archive_streams_excludes_non_event_bearing():
+    """Archive's STREAMS list contains exactly the event_bearing=True entries."""
+    from central.archive import STREAMS as ARCHIVE_STREAMS
+
+    expected = [(s.name, s.subject_filter) for s in STREAMS if s.event_bearing]
+    assert ARCHIVE_STREAMS == expected
+    archive_names = {name for name, _ in ARCHIVE_STREAMS}
+    for s in STREAMS:
+        if s.event_bearing:
+            assert s.name in archive_names
+        else:
+            assert s.name not in archive_names
+
+
+def test_dashboard_streams_matches_dashboard_flag():
+    """GUI's DASHBOARD_STREAMS matches [s.name for s in STREAMS if s.dashboard]."""
+    from central.gui.routes import DASHBOARD_STREAMS
+
+    expected = [s.name for s in STREAMS if s.dashboard]
+    assert DASHBOARD_STREAMS == expected