conandeps: add progress output, silence Conan's SyntaxWarnings, allow Python 3.12+

- Progress lines on stderr for each of the three graph resolutions (with
  package/missing counts and timing) so a slow remote no longer looks like
  a hang; -q suppresses them. stdout remains the clean report.
- --verbose now streams Conan's output live via a tee instead of dumping it
  at the end.
- Filter SyntaxWarning/DeprecationWarning before importing conans: Conan 1.x
  modules trip the stricter escape-sequence checks of recent Pythons and
  printed a screenful of noise on 3.14.
- Drop the <3.12 requires-python ceiling. Conan 1.66 falls back to importlib
  where imp is missing; verified working on 3.14. Fix the Containerfile and
  docs that claimed otherwise.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYNdaGDrpaqDyT8QtrTQbM

pyproject.toml

@@ -6,8 +6,7 @@ readme = "README.md"
 license = "MIT"
 license-files = ["LICENSE"]
 authors = [{ name = "Ole-Morten Duesund" }]
-# Conan 1.x imports the `imp` module, which was removed in Python 3.12.
-requires-python = ">=3.8,<3.12"
+requires-python = ">=3.8"
 dependencies = ["conan>=1.66,<2"]
 
 [project.scripts]