fix: nightly hardening - HTTP endpoint URL validation

[mouse-value-add]

Problem

The HTTP provider accepted any string without validating URL shape. Misconfigured endpoints (for example or malformed ) fail later during runtime with less actionable errors.

Approach

• Added validation with a Pydantic field validator.
• Enforced / schemes only.
• Required a host () so malformed URLs are rejected at config load time.
• Added focused unit tests for accepted and rejected endpoint inputs.

Verification

• Ran: ============================= test session starts ==============================
  platform darwin -- Python 3.9.6, pytest-8.4.2, pluggy-1.6.0
  rootdir: /private/tmp/oss-nightly/PromptLens
  configfile: pyproject.toml
  plugins: anyio-4.12.1, asyncio-1.2.0, cov-7.1.0
  asyncio: mode=strict, debug=False, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function
  collected 3 items

tests/test_provider_config_endpoint_validation.py ... [100%]

=============================== warnings summary ===============================
promptlens/models/tools.py:14
/private/tmp/oss-nightly/PromptLens/promptlens/models/tools.py:14: PydanticDeprecatedSince20: Support for class-based config is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.12/migration/
class ToolParameter(BaseModel):

promptlens/models/test_case.py:10
/private/tmp/oss-nightly/PromptLens/promptlens/models/test_case.py:10: PydanticDeprecatedSince20: Support for class-based config is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.12/migration/
class TestCase(BaseModel):

promptlens/models/test_case.py:66
/private/tmp/oss-nightly/PromptLens/promptlens/models/test_case.py:66: PydanticDeprecatedSince20: Support for class-based config is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.12/migration/
class GoldenSet(BaseModel):

promptlens/models/config.py:115
/private/tmp/oss-nightly/PromptLens/promptlens/models/config.py:115: PydanticDeprecatedSince20: Support for class-based config is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.12/migration/
class RunConfig(BaseModel):

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
================================ tests coverage ================================
_______________ coverage: platform darwin, python 3.9.6-final-0 ________________

Name Stmts Miss Cover

promptlens/init.py 3 0 100%
promptlens/main.py 3 3 0%
promptlens/cli.py 169 169 0%
promptlens/exporters/init.py 6 6 0%
promptlens/exporters/base.py 15 15 0%
promptlens/exporters/csv_exporter.py 26 26 0%
promptlens/exporters/html_exporter.py 38 38 0%
promptlens/exporters/json_exporter.py 16 16 0%
promptlens/exporters/markdown_exporter.py 77 77 0%
promptlens/judges/init.py 3 3 0%
promptlens/judges/base.py 15 15 0%
promptlens/judges/llm_judge.py 71 71 0%
promptlens/judges/parser.py 107 107 0%
promptlens/judges/prompts.py 30 30 0%
promptlens/loaders/init.py 4 4 0%
promptlens/loaders/base.py 14 14 0%
promptlens/loaders/json_loader.py 23 23 0%
promptlens/loaders/yaml_loader.py 34 34 0%
promptlens/models/init.py 4 0 100%
promptlens/models/config.py 53 1 98%
promptlens/models/result.py 60 13 78%
promptlens/models/test_case.py 25 0 100%
promptlens/models/tools.py 74 34 54%
promptlens/providers/init.py 3 3 0%
promptlens/providers/anthropic.py 52 52 0%
promptlens/providers/base.py 23 23 0%
promptlens/providers/factory.py 21 21 0%
promptlens/providers/google.py 47 47 0%
promptlens/providers/http.py 67 67 0%
promptlens/providers/openai.py 57 57 0%
promptlens/providers/you.py 57 57 0%
promptlens/runners/init.py 2 2 0%
promptlens/runners/runner.py 96 96 0%
promptlens/utils/init.py 1 1 0%
promptlens/utils/cost.py 15 15 0%
promptlens/utils/diff.py 25 25 0%
promptlens/utils/retry.py 21 21 0%
promptlens/utils/timing.py 24 24 0%

TOTAL 1381 1210 12%
Coverage HTML written to dir htmlcov
======================== 3 passed, 4 warnings in 0.30s =========================

• Result: 3 tests passed.

Risks

• Users with previously accepted but malformed endpoints will now fail fast at config parsing.
• This is intentional hardening; risk is limited to invalid configs.

Rollback Plan

• Revert this PR commit to restore previous permissive endpoint behavior.
• If needed, relax validation rules in in a follow-up PR.