Updates settings pattern

[AndyRae]

Pull Request Contents

♻️ Refactor

Description

Refactors settings configuration, made less brittle and clearer.

• Configuring hasn't changed - all environment variables.
• Adds Pydantic settings as the model
• Updates tests

With the introduction of Pydantic - devs will need to run uv sync on their environment.

Related Issues or other material

• This PR relates to one or more issues, detailed below

• Closes Configuration management #40

✅ Added/updated tests?

• This PR contains relevant tests
  • Or doesn't need to per the below explanation

• I've completed all actions and tasks detailed in the PR Template

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/hutch_bunny
cli.py	34	34	0%	1–63
daemon.py	46	46	0%	1–86
src/hutch_bunny/core
db_manager.py	72	38	47%	35, 49, 60, 71, 87, 89, 91, 93, 95, 109, 121–126, 129–132, 163–182, 194–199, 208–211, 219
enums.py	8	1	88%	23
execute_query.py	28	28	0%	1–66
obfuscation.py	15	1	93%	62
parser.py	5	5	0%	1–22
results_modifiers.py	13	13	0%	1–45
setting_database.py	27	17	37%	17, 20, 28–63
settings.py	43	2	95%	64, 85
task_api_client.py	32	32	0%	1–92
src/hutch_bunny/core/rquest_dto
activity_job.py	12	12	0%	1–36
base_dto.py	6	2	67%	3, 7
cohort.py	14	4	71%	17, 32–34
file.py	12	1	92%	24
group.py	14	4	71%	19, 34–36
query.py	38	14	63%	32, 51–52, 79, 102–116
result.py	15	1	93%	38
rule.py	50	32	36%	28–31, 41–52, 64–72, 85–101
src/hutch_bunny/core/solvers
availability_solver.py	180	77	57%	148–149, 154, 181, 197–223, 231, 255–275, 291–300, 324–330, 337–409, 419–426, 433–473, 492–508, 522–528
query_solvers.py	150	21	86%	35, 141, 156–181, 252
TOTAL	971	385	60%

Tests	Skipped	Failures	Errors	Time
25	0 💤	4 ❌	0 🔥	1.078s ⏱️