Fix packaged rig profile resolution

[morozsm]

Summary

Fixes #1902.

Centralizes built-in rig profile lookup behind core-owned resource helpers so packaged consumers can load bundled TOML profiles without monkeypatching app-specific paths. The CLI model resolver, profile registry, and Yaesu CAT string-profile loading now use the same supported resolver.

Compatibility

• Public API: additive/compatible. Existing load_rig(path) and discover_rigs(path) remain available for explicit filesystem profiles.
• CLI: no syntax changes.
• Config files: no format changes.
• rigctld wire behavior: no changes.
• Packaged apps: built-in profiles are resolved from package resources first, with repo-root fallback for editable checkouts.

Tests

• uv run pytest -q tests/test_rig_loader.py tests/test_profiles_runtime.py tests/test_profiles_routing.py tests/test_ftx1_radio.py tests/test_yaesu_cli_factory.py tests/test_cli_model.py
• uv run ruff check src/rigplane/profiles/rig_loader.py src/rigplane/profiles/__init__.py src/rigplane/cli/__init__.py src/rigplane/backends/yaesu_cat/radio.py src/rigplane/backends/factory.py tests/test_ftx1_radio.py tests/test_rig_loader.py tests/test_yaesu_cli_factory.py
• git diff --check

[morozsm]

Agent Review: PASS
Reviewed head SHA: 758e7be