Halkyon's shared packages

A pub workspace of the Dart packages Halkyon's apps share: halkyon_ui,
Halkyon's look (the theme, fonts, layout and shared widgets, with texts
in English and German), halkyon_core's low-level primitives and
halkyon_interop's cross-app contracts. Dart 3.13 with LeanCode's lints,
configured once at the root; apps take a package by git, pinned to a
signed commit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_ui/analysis_options.yaml

@@ -0,0 +1,11 @@
+# The workspace's lint rules (see ../../analysis_options.yaml).
+include: ../../analysis_options.yaml
+
+analyzer:
+  exclude:
+    - build/**
+    # Generated by gen-l10n (see l10n.yaml).
+    - lib/l10n/halkyon_ui_localizations*.dart
+
+formatter:
+  trailing_commas: preserve