new(pyqt5): per-binding sub-recipes (Top 300 #591)

[tannevaled]

Summary

PyQt5 split into 11 recipes: one meta + 10 per-binding sub-recipes
(QtCore, QtDBus, QtNetwork, QtSql, QtTest, QtXml, QtGui, QtSvg,
QtPrintSupport, QtWidgets).

The original monolithic recipe iterated all 10 bindings in a single
CI job via pip install --config-settings=--enable=<binding> in a
shell loop. Each binding's link peaks at 6-8 GB RAM (sip-generated
.cpp), so the 7 GB GH-Linux runner OOM'd on every binding and GHA
cancelled the workflow at 1h33min (CI run 26712172867: 6/10 bindings
SIGKILL'd, 4 still queued).

The split gives each binding its own CI job with its own 6 h timeout
and an independent runner.

Topology

QtCore         (foundation, no PyQt5 deps)
  ├── QtDBus       (deps QtCore)
  ├── QtNetwork    (deps QtCore)
  ├── QtSql        (deps QtCore)
  ├── QtTest       (deps QtCore)
  ├── QtXml        (deps QtCore)
  └── QtGui        (deps QtCore, HEAVY)
        ├── QtSvg          (deps QtGui)
        ├── QtPrintSupport (deps QtGui)
        └── QtWidgets      (deps QtGui, HEAVIEST)
pyqt5 (meta)     (deps all 10)

Sibling deps are pinned exactly (={{version}}) so the meta sees one
coherent install across all 10 prefixes.

PyQt5 ships __init__.py with __path__ = pkgutil.extend_path(...),
making it a true namespace package. Each sub-binding drops its own
PyQt5/<Binding>.so into its own prefix's
share/python/site-packages/PyQt5/, and pkgx stacks the
PYTHONPATH so pkgutil.extend_path merges them at import time.

Preserved from the monolithic recipe

• The awk patch for confirm-license = true in pyproject.toml
  (commit 495169a, which itself fixed YAML block-scalar parsing of
  the earlier sed a\ form).
• CXXFLAGS=-g0 / CFLAGS=-g0 / MAKEFLAGS=-j1 memory discipline.
• --no-build-isolation / --no-deps so pantry's CXXFLAGS reach the
  compiler and pip does not refetch PyQt5-sip from PyPI.

Merge order (chicken-and-egg)

All 11 recipes ship in this single PR. The non-foundation bindings
and the meta will FAIL on Linux x64 CI until QtCore is bottled to
dist.pkgx.dev — same shape as the font-util / xserver and
tk / tcl splits in pantry history.

Maintainers: please merge / bottle in topological order:

1. QtCore first (no PyQt5 deps).
2. Layer 2 (after QtCore is on dist.pkgx.dev):
   QtDBus, QtNetwork, QtSql, QtTest, QtXml, QtGui.
3. Layer 3 (after QtGui is on dist.pkgx.dev):
   QtSvg, QtPrintSupport, QtWidgets.
4. Meta pyqt5 last.

Cross-checked against homebrew's pyqt@5 (one big build, but their
runners have more RAM) and nixpkgs's python3.pkgs.pyqt5 (same).
Neither has the GHA-7 GB constraint we do, hence the split.

Closes part of #99 (Top 300 #591).

Test plan

• All 11 package.yml parse as valid YAML.
• QtCore Linux x64 CI build (no inter-PyQt5 deps) — first
  bottling pass.
• Layer 2 + Layer 3 + meta — second / third pass after QtCore
  lands.
• Smoke test on darwin/aarch64 after all 10 bindings ship.

🤖 Generated with Claude Code

[tannevaled]

Draft — PyQt5 sdist build hits 2 issues simultaneously:

1. License prompt blocks CI: configure asks 'Type yes to accept the terms of the license'. Non-interactive CI hangs.
2. OOM: SIGKILL after 13+ minutes — PyQt5's C++ binding generation is memory-heavy.

Fix needs:

• Bypass license: pass --confirm-license to configure.py (sip-build), or set up python-venv.sh to forward pip --config-settings
• Memory: build with -j1 or restrict bindings (PyQt5 has many submodules each compiled separately)

Both require modifying brewkit's python-venv.sh helper or a custom build flow. Deferring.