refactor(client): constructor-injectable config, lazy settings, single close path

[Datata1]

Implements plans/refactor/03-client-config-lifecycle.md:

• config.py no longer instantiates Settings() at import time; token is optional on the Settings model. 'import codesphere' now succeeds without any environment variables
• CodesphereSDK(token=..., base_url=..., timeout=..., http_client=...)
  with resolution order: explicit argument > CS_* env (.env honored) >
  built-in default. A missing token raises AuthenticationError at construction (previously a raw pydantic ValidationError at import; the purpose-built exception was never raised)
• Fix dead CS_BASE_URL: the transport no longer defaults its own base_url, so the configured value actually applies; two SDK instances with different tokens/URLs can now coexist in one process
• APIHttpClient becomes a dumb transport: full config passed in, no settings access, dynamic get/post/... setattr loop removed, BaseModel re-dump removed (serialization owned solely by execute_operation)
• One close path: aexit delegates to close(exc_type, exc_val, exc_tb) on both SDK and transport
• New tests/test_sdk_config.py: import-without-env (empty-env subprocess), token/base_url/timeout resolution order, two-client isolation via httpx.MockTransport; conftest fixtures no longer patch a settings singleton
• config.py and http_client.py removed from the ty ratchet
• README documents constructor configuration

Behavior change (fix): startup failure moves from import time to CodesphereSDK() construction and is now AuthenticationError.

[github-actions]

🛡️ Bandit Security Scan Results

✅ No security issues found by Bandit.

[github-actions]

Pytest Coverage Report

File	Stmts	Miss	Branch	BrPart	Cover	Missing
__init__.py	9	0	0	0	100%
client.py	40	0	6	0	100%
config.py	9	0	0	0	100%
exceptions.py	94	32	38	22	59%	25->30, 40–42, 53->58, 54->55, 55, 73->74, 74, 85–87, 101–104, 106–107, 148–151, 158–160, 196->197, 197–199, 204->205, 205, 206->207, 207, 210->211, 211, 214, 215->216, 216, 217->218, 218–219, 222
http_client.py	49	6	6	2	85%	42->exit, 52->exit, 87–88, 90–91, 96–97
utils.py	27	16	18	15	31%	12->13, 13–14, 27–33, 35–36, 41–44, 46
core
__init__.py	4	0	0	0	100%
base.py	47	0	2	0	100%
handler.py	59	3	18	0	96%	80–82
operations.py	15	0	0	0	100%
resources
__init__.py	0	0	0	0	100%
resources/metadata
__init__.py	3	0	0	0	100%
operations.py	6	0	0	0	100%
resources.py	13	0	0	0	100%
schemas.py	28	0	0	0	100%
resources/team
__init__.py	5	0	0	0	100%
operations.py	8	0	0	0	100%
resources.py	11	0	0	0	100%
schemas.py	27	0	0	0	100%
resources/team/domain
__init__.py	0	0	0	0	100%
manager.py	21	0	0	0	100%
operations.py	12	0	0	0	100%
resources.py	26	5	0	0	81%	31, 33, 36, 39–40
schemas.py	34	0	0	0	100%
resources/team/usage
__init__.py	3	0	0	0	100%
manager.py	45	2	8	2	92%	99->102, 102, 162->165, 165
operations.py	4	0	0	0	100%
schemas.py	85	15	14	13	72%	69->70, 70, 84–85, 88, 96–99, 114–115, 118, 126–129
resources/workspace
__init__.py	5	0	0	0	100%
operations.py	12	0	0	0	100%
resources.py	16	2	4	2	80%	13->14, 14, 19->20, 20
schemas.py	99	14	6	6	81%	100–101, 103–109, 115–116, 118, 142, 161
resources/workspace/envVars
__init__.py	3	0	0	0	100%
models.py	30	2	12	4	86%	34->36, 36–37, 39->exit
operations.py	7	0	0	0	100%
schemas.py	4	0	0	0	100%
resources/workspace/git
__init__.py	3	0	0	0	100%
models.py	20	0	4	0	100%
operations.py	8	0	0	0	100%
schema.py	4	0	0	0	100%
resources/workspace/landscape
__init__.py	3	0	0	0	100%
models.py	99	7	36	8	89%	28->29, 29, 126->129, 132->135, 156->157, 157–158, 160->155, 163->164, 164, 168–170
operations.py	11	0	0	0	100%
resources.py	0	0	0	0	100%
schemas.py	297	29	10	4	89%	122–123, 126, 131–132, 135–136, 139, 144–146, 149–150, 153, 260, 267–268, 343–345, 347–349, 351–352, 467–468, 475–476
resources/workspace/logs
__init__.py	3	0	0	0	100%
models.py	155	86	62	54	35%	41–42, 48, 50–52, 54, 57–58, 61, 64–65, 67–70, 72–73, 76–77, 79–80, 82–83, 85–87, 89–90, 92–96, 98–99, 101–103, 105–110, 123–124, 214–216, 225–227, 236–238, 248–257, 267–276, 286–295
operations.py	5	0	0	0	100%
schemas.py	19	0	0	0	100%
TOTAL	1487	219	244	132	80%

Test Execution Summary

Tests	Skipped	Failures	Errors	Time
276	0 💤	0 ❌	0 🔥	2.862s ⏱️