chore: bump dev toolchain to Python 3.14, add HA 2026-latest matrix cell

[DefinitelyADev]

Summary

Adds a 4th CI matrix cell on Python 3.14 / HA 2026-latest, moves the non-matrix jobs (lint, type-check, validate, pre-commit) to py3.14, and bumps requirements-dev.txt floors to homeassistant>=2026.5.4 and pytest-homeassistant-custom-component>=0.13.333. This unblocks Dependabot PRs #30 and #31, which were stuck because both target dependencies require Python ≥3.14 / ≥3.14.2.

Why

• phacc 0.13.317+ → Requires-Python >=3.14
• HA 2026.3.0+ → Requires-Python >=3.14.2

The matrix was capped at py3.13, so pip install -r requirements-dev.txt failed on PRs that bumped either floor. The existing py3.13 / HA 2026 / phacc==0.13.316 cell stays as the "last py3.13" boundary — the new cell sits beside it for the moving HA head.

Changes

.github/workflows/ci.yml

• Add 4th matrix cell: py3.14 / ha-version=2026-latest / phacc==0.13.333.
• validate, type-check, lint jobs: setup-python 3.13 → 3.14.

.github/workflows/pre-commit.yml

• setup-python 3.13 → 3.14.

requirements-dev.txt

• homeassistant>=2023.6.0 → >=2026.5.4.
• pytest-homeassistant-custom-component>=0.13.298,<0.13.317 → >=0.13.333. The upper cap existed only to keep py3.13 dev installs away from py3.14-gated phacc — no longer needed since the dev floor is now py3.14.

AGENTS.md and CLAUDE.md

• "3-cell matrix" → "4-cell matrix"; note that non-matrix jobs are on py3.14 because of the requirements-dev.txt floor.

Pre-flight already done

• ✅ actions/setup-python@v6 resolves Python 3.14.2/3/4/5 on ubuntu-24.04 (latest stable 3.14.5).
• ✅ All dev tools (mypy 2.1.0, pre-commit 4.6.0, black 26.5.1, isort 8.0.1, flake8 7.3.0, ruff 0.15.14, pyright 1.1.409, pytest 9.0.3, pytest-cov 7.1.0, voluptuous 0.16.0, phacc 0.13.333, homeassistant 2026.5.4) ship py3.14-compatible wheels.
• Not run locally: python check_all.py — toolchain now requires py3.14.2+ which isn't installed locally. CI is the verification.

Test plan

• All 4 matrix cells pass test
• lint, type-check, validate, pre-commit, hassfest, hacs-validation pass on py3.14
• codecov/patch and codecov/project resolve (currently gated to ha-version == '2026', the existing py3.13 cell — unchanged)
• After merge, @dependabot rebase chore: update pytest-homeassistant-custom-component requirement from <0.13.317,>=0.13.298 to >=0.13.333,<0.13.334 #30 and chore: update homeassistant requirement from >=2023.6.0 to >=2026.5.4 #31 — both should turn green or auto-close as obsolete

Not in scope

• manifest.json HA floor (2024.4.0) stays — runtime support for older HA is independent of dev tooling.
• CHANGELOG entry — convention has been to add CI/dev-tooling entries at release time, not per-PR.
• .github/dependabot.yml ignore list — no longer needed if this PR works; revisit only if the matrix bump is reverted.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.51%. Comparing base (21ca35c) to head (b4c7465).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #39   +/-   ##
=======================================
  Coverage   91.51%   91.51%           
=======================================
  Files          10       10           
  Lines         849      849           
  Branches       79       79           
=======================================
  Hits          777      777           
  Misses         49       49           
  Partials       23       23           

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