Add WordClouds gramplet

[dsblank]

Summary

Adds three word-cloud gramplets — Given Name Word Cloud, Surname Word
Cloud, and Place Word Cloud — that render names/places as a
size-weighted, click-to-navigate word cloud instead of the old plain-text
link list.

• wordcloudwidget.py — a Cairo/Pango WordCloudWidget (Gtk.DrawingArea)
  that lays out words with a spiral placement algorithm, sized and colored
  by frequency.
• slideroption.py — a SliderOption/GuiSliderOption pair (a
  NumberOption rendered as a slider + text entry), registered via
  BasePluginManager.register_option() so no changes to Gramps core are
  required.
• cloudgramplet.py — shared CloudGramplet base class handling the
  common option set (top-N count, colors, layout quality, filter
  missing/unknown values) and word-cloud wiring.
• givennamewordcloudgramplet.py, surnamewordcloudgramplet.py,
  placewordcloudgramplet.py — the three concrete gramplets.

This is based on ideas from ClmntPnd's Gramps core PR
gramps-project/gramps#2223,
which added the WordCloudWidget-based rendering (including a Place Cloud
gramplet and autosave_options support) directly to Gramps core. This PR
adapts that work into a self-contained addon instead, so it:

• Works with unmodified, current stable Gramps releases (no core patches).
• Uses new gramplet ids/class names (Given Name Word Cloud /
  GivenNameWordCloudGramplet, Surname Word Cloud /
  SurnameWordCloudGramplet, Place Word Cloud /
  PlaceWordCloudGramplet) that are distinct from the built-in
  Given Name Cloud / Surname Cloud gramplets, to avoid any plugin
  registration collision between the addon and the core gramplets of the
  same name.
• Uses the standard Save-button option flow (rather than the core-patched
  autosave_options instant-apply behavior), since that required a
  grampletpane.py change.

Test plan

• tests/test_imports.py — all modules import cleanly; each gramplet
  class is a proper Gramplet subclass.
• tests/test_wordcloudwidget.py — font-size/color interpolation and
  bounding-box overlap helpers.
• tests/test_slideroption.py — SliderOption value/min/max/step
  behavior and GuiSliderOption widget wiring (run under xvfb-run,
  since it needs a real display connection).
• tests/test_cloudgramplet_logic.py — get_items() for each
  gramplet against a real in-memory Gramps database, including the
  filter_missing option and backlink-based place filtering.
• Manual: install the addon, open each of the three gramplets in a
  running Gramps 6.1, verify word clicks navigate correctly and
  options apply on Save.

[GaryGriffin]

One unittest had warning:

python3 -m unittest WordClouds.tests.test_imports     
/Users/GrampsTest61/gtk/inst/lib/python3.14/site-packages/gi/overrides/__init__.py:159: PyGIDeprecationWarning: GLib.unix_signal_add_full is deprecated; use GLibUnix.signal_add_full instead
  value = getattr(proxy, attr)
....
----------------------------------------------------------------------
Ran 4 tests in 0.448s

OK

Another unittest popped up a WarningDialog. This could be Mac-specific as gexiv2 is built within the Mac bundle and is not in a separate pip package. Plz confirm that you do not see this on Linux/Win.

python3 -m unittest WordClouds.tests.test_cloudgramplet_logic

/Users/GrampsTest61/gtk/inst/lib/python3.14/site-packages/gi/events.py:803: DeprecationWarning: 'asyncio.AbstractEventLoopPolicy' is deprecated and slated for removal in Python 3.16
  AbstractEventLoopPolicy = getattr(asyncio, "AbstractEventLoopPolicy", object)
/Users/GrampsTest61/gtk/inst/lib/python3.14/site-packages/gi/events.py:890: DeprecationWarning: 'asyncio.get_event_loop_policy' is deprecated and slated for removal in Python 3.16

.......
----------------------------------------------------------------------
Ran 7 tests in 5.238s

OK

@dsblank - Plz confirm if I can merge these with these warnings.
@eduralph - any issues with CI if these tests are merged?

[dsblank]

@GaryGriffin The deprecation warnings in test_imports are harmless (upstream PyGObject/asyncio noise, not from this addon).

I dug into the WarningDialog and it's not a WordClouds bug — it's core Gramps. gramps/plugins/gramplet/gramplet.gpr.py has module-level code that pops a MessageHideDialog ("GExiv2 module not loaded") whenever has_display() returns True and GExiv2 isn't importable. Our test's make_database("sqlite") call goes through BasePluginManager.get_instance() (gramps/gen/db/utils.py), which scans every registered .gpr.py, including that core one — so this fires for any addon test that ends up touching the plugin manager, on any machine with a live display and no GExiv2, not just WordClouds. On Linux here it doesn't reproduce because there's no display attached in that environment.

Your read on it being Mac-specific was right — it's the classic Mac GExiv2-bundling gap, unrelated to this PR's code.

For now: re-running with GDK_BACKEND=- set (per this repo's documented test-running convention) should suppress it, since that makes has_display() return False even with a physical display attached.

@eduralph — heads up, this also affects the new shared harness on gramps60: neutralize_gui_dialogs() in tests/gramps_test_env.py stubs out ErrorDialog/WarningDialog/OkDialog/etc. but not MessageHideDialog, which is what core's gramplet.gpr.py uses here. Since get_plugin_manager_and_registry() scans PLUGINS_DIR (core's own plugins tree, not just addons), test_plugin_registration.py / make.py test could hang on this exact modal on a GExiv2-less host with a display. Not a problem in the CI container itself since the Dockerfile bundles gir1.2-gexiv2-0.10, but it'll bite local runs. Following up with a comment on #980 about it.

Safe to merge WordClouds as-is from my side.