fix(viewer): drop undefined MAX_ENTITIES_PER_ANNOTATION from __all__

[Anai-Guo]

Problem

viewer/server/runtime.py exports MAX_ENTITIES_PER_ANNOTATION in __all__, but no such name exists — it is not defined in the module, and grep over the whole repository finds exactly one occurrence: the __all__ entry itself. There is also no annotation-limit logic anywhere that such a constant would serve, so it looks like a leftover from a constant that was planned or removed (MAX_ADJACENCY_IDS, right above it, does exist).

Checked the rest of the list with an AST pass — the other 8 entries all resolve:

__all__ entries: 9
defined:         8 / 9
MISSING:        ['MAX_ENTITIES_PER_ANNOTATION']

Impact

__all__ is what import * iterates, so the star-import form of this module raises. The module imports only stdlib, so this reproduces standalone:

Before

>>> from viewer.server.runtime import *
AttributeError: module 'runtime' has no attribute 'MAX_ENTITIES_PER_ANNOTATION'

After

>>> from viewer.server.runtime import *
OK: star-import succeeded

The existing importers (viewer/server/server.py, tests/test_viewer_re_server.py) all use explicit from ... import (...) lists, so nothing in the repo hits this today — but it also means the entry silently breaks import *, help(), and any autodoc pass over the module.

Fix

Removes the one stale line. No other changes.

🤖 Generated with Claude Code

[NiJingzhe]

Thanks @Anai-Guo — nice catch and a textbook bug report: verified the reproduction, confirmed the stale entry, and appreciated that you checked the other 8 names in __all__ before touching anything. Merged after the CI matrix went green. 👍