deps: pin requires-python = ">=3.14"; commit uv.lock

Match CI + runtime target exactly — both run Python 3.14, so the
package metadata signals consumers that we don't test against 3.12/3.13.

uv.lock is tracked so the test job's `uv venv` resolution is
reproducible (currently the test job installs the editable package
without consulting the lockfile; future work could wire `uv sync` in).
Lockfile resolves 179 packages against Python 3.14.4.

ci-requirements.md updated to drop the prior "permissive lower bound"
caveat.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -6,7 +6,7 @@ build-backend = "setuptools.build_meta"
 name = "fabledassistant"
 version = "0.1.0"
 description = "Self-hosted note-taking and task-tracking app with LLM integration"
-requires-python = ">=3.12"
+requires-python = ">=3.14"
 dependencies = [
     "quart>=0.19",
     "sqlalchemy[asyncio]>=2.0",