fix(lint): restore Python 3.9 compatibility (#58)

Add deferred annotation evaluation, enforce Python 3.9 linter coverage in CI, and publish synchronized plugin version 2.4.4.

.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "diagram-design",
   "description": "Create branded architecture, IT current-state, flowchart, sequence, state machine, ER/data model, timeline, swimlane, quadrant, radar/spider, loop/flywheel, nested, tree, org chart, layer stack, Venn, pyramid/funnel, bar, line, Gantt and scatter charts, high-level, process, medallion, data flow, DP integration, or DP security matrix diagrams as standalone HTML/SVG/PNG. Redraw .drawio/.drawio.png/.drawio.svg or Mermaid .mmd sources at a chosen size/detail; onboard brand tokens from a website; add semantic patterns, callouts, accessible motion, or sketchy/hand-drawn styling.",
-  "version": "2.4.3",
+  "version": "2.4.4",
   "author": {
     "name": "Cathryn Lavery",
     "url": "https://github.com/cathrynlavery"

.codex-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "diagram-design",
   "description": "Create branded architecture, IT current-state, flowchart, sequence, state machine, ER/data model, timeline, swimlane, quadrant, radar/spider, loop/flywheel, nested, tree, org chart, layer stack, Venn, pyramid/funnel, bar, line, Gantt and scatter charts, high-level, process, medallion, data flow, DP integration, or DP security matrix diagrams as standalone HTML/SVG/PNG. Redraw .drawio/.drawio.png/.drawio.svg or Mermaid .mmd sources at a chosen size/detail; onboard brand tokens from a website; add semantic patterns, callouts, accessible motion, or sketchy/hand-drawn styling.",
-  "version": "2.4.3",
+  "version": "2.4.4",
   "author": {
     "name": "Cathryn Lavery",
     "url": "https://github.com/cathrynlavery"

.github/workflows/ci.yml

@@ -51,6 +51,27 @@ jobs:
       - name: Validate Claude marketplace package without warnings
         run: npx --yes @anthropic-ai/claude-code@2.1.229 plugin validate . --strict
 
+  python39-compat:
+    name: Python 3.9 Compatibility
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.9"
+
+      - name: Verify linter compatibility
+        run: |
+          python scripts/test-lint-a11y.py
+          python scripts/lint-skin.py --all --baseline
+
   validate:
     name: Lint & Verify (${{ matrix.os }}, Python ${{ matrix.python-version }})
     strategy:

scripts/lint-skin.py

@@ -5,6 +5,8 @@ Pre-2.0 examples may legitimately fail because they were built against an older
 skin. Use ``--all --baseline`` to skip those documented legacy files.
 """
 
+from __future__ import annotations
+
 import argparse
 import hashlib
 import re