build: Melos, a Dart check and every path for the single repository

- Melos 8.9 as the root's dev dependency, with scripts across the
  workspace (analyze, test:dart, test:flutter, generate, check) and its
  filters (--diff, --include-dependents); cli_util overridden to 0.5.2
  for it, since Learn's flutter_launcher_icons asks for 0.4 and uses only
  its logger, unchanged in 0.5.
- tool/check.dart in place of tool/check.sh: packages, formatting of our
  own files, analysis, the tools' tests, then every package's tests
  through Melos (--changed-since=<commit> for only what changed and what
  depends on it). tool/pre-push is the hook: the signature check, then
  the checks. CI generates every server's code and runs the same check.
- The images build from the root with a workspace narrowed to what they
  need (tool/workspace_only.sh); compose, the deploy's migration test,
  the snap, the release script, the editor's launch files and Learn's
  asset tools (run from apps/learn) follow the new layout.
- The project's source is named as project-halkyon/halkyon (source link,
  snap, F-Droid listing, release uploads); the AGPL packages carry the
  licence's own text.

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

pubspec.lock

@@ -73,6 +73,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.0"
+  ansi_styles:
+    dependency: transitive
+    description:
+      name: ansi_styles
+      sha256: "9c656cc12b3c27b17dd982b2cc5c0cfdfbdabd7bc8f3ae5e8542d9867b47ce8a"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.3.2+1"
   appflowy_editor:
     dependency: transitive
     description:
@@ -91,7 +99,7 @@ packages:
     source: hosted
     version: "4.3.0"
   args:
-    dependency: transitive
+    dependency: "direct dev"
     description:
       name: args
       sha256: d0481093c50b1da8910eb0bb301626d4d8eb7284aa739614d2b394ee09e3ea04
@@ -250,14 +258,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.2.0"
-  cli_util:
+  cli_launcher:
     dependency: transitive
     description:
-      name: cli_util
-      sha256: ff6785f7e9e3c38ac98b2fb035701789de90154024a75b6cb926445e83197d1c
+      name: cli_launcher
+      sha256: d2dd1baf7ae4ff1550e731dcb8fe669a5c652903e833f75359c178222c44214e
       url: "https://pub.dev"
     source: hosted
-    version: "0.4.2"
+    version: "0.3.4"
+  cli_util:
+    dependency: "direct overridden"
+    description:
+      name: cli_util
+      sha256: "71e43f1976c3eae2d9468a5b4d6600bf8cae61508b87f27fa1799228935d48ab"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.2"
   clock:
     dependency: transitive
     description:
@@ -306,6 +322,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
+  conventional_commit:
+    dependency: transitive
+    description:
+      name: conventional_commit
+      sha256: c40b1b449ce2a63fa2ce852f35e3890b1e182f5951819934c0e4a66254bc0dc3
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.1+1"
   convert:
     dependency: transitive
     description:
@@ -856,6 +880,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.4"
+  graphs:
+    dependency: transitive
+    description:
+      name: graphs
+      sha256: "741bbf84165310a68ff28fe9e727332eef1407342fca52759cb21ad8177bb8d0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
   hex:
     dependency: transitive
     description:
@@ -1133,6 +1165,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.0.1"
+  melos:
+    dependency: "direct dev"
+    description:
+      name: melos
+      sha256: "140e51d7990b5134663e64b39e19d3b64ead16382e69127c205942c91e752b16"
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.9.0"
   meta:
     dependency: transitive
     description:
@@ -1149,6 +1189,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
+  mustache_template:
+    dependency: transitive
+    description:
+      name: mustache_template
+      sha256: "17a8de9072575bb1a3237b90ed1f756b2189995b334df2ad12b7cdd76b13f3ce"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.6"
   nanoid:
     dependency: transitive
     description:
@@ -1361,10 +1409,10 @@ packages:
     dependency: transitive
     description:
       name: platform
-      sha256: a36d119c13416516a7b5913fbe8af8531e11633d784c550b2125f76c758524ec
+      sha256: "5d6b1b0036a5f331ebc77c850ebc8506cbc1e9416c27e59b439f917a902a4984"
       url: "https://pub.dev"
     source: hosted
-    version: "3.2.0"
+    version: "3.1.6"
   plugin_platform_interface:
     dependency: transitive
     description:
@@ -1413,6 +1461,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.0.6"
+  prompts:
+    dependency: transitive
+    description:
+      name: prompts
+      sha256: "3773b845e85a849f01e793c4fc18a45d52d7783b4cb6c0569fad19f9d0a774a1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.0"
   provider:
     dependency: transitive
     description:
@@ -1429,6 +1485,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.1"
+  pub_updater:
+    dependency: transitive
+    description:
+      name: pub_updater
+      sha256: "3aadeb8c68d15ef9d117b36474ddcc543b48ae1e64f7dd71407da26df66bf7c8"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.0"
+  pubspec_parse:
+    dependency: transitive
+    description:
+      name: pubspec_parse
+      sha256: c38b81cbf34450b67e0265d73433569d12e34782e30ed769c9cc99c9d5f2e796
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.6.0"
   punycoder:
     dependency: transitive
     description:
@@ -1909,7 +1981,7 @@ packages:
     source: hosted
     version: "1.2.2"
   test:
-    dependency: transitive
+    dependency: "direct dev"
     description:
       name: test
       sha256: ca578dc12bb8b2f40b67b7d3bd2fac4f31c01a6ff7130a14e2597b919934507f