fix: improve MiniMax adaptor from PR #318 review (#319)

* feat: add MiniMax AI as LLM platform adaptor

Original implementation by octo-patch in PR #318.
This commit includes comprehensive improvements and documentation.

Code Improvements:
- Fix API key validation to properly check JWT format (eyJ prefix)
- Add specific exception handling for timeout and connection errors
- Remove unused variable in upload method

Dependencies:
- Add MiniMax to [all-llms] extra group in pyproject.toml

Tests:
- Remove duplicate setUp method in integration test class
- Add 4 new test methods:
  * test_package_excludes_backup_files
  * test_upload_success_mocked (with OpenAI mocking)
  * test_upload_network_error
  * test_upload_connection_error
  * test_validate_api_key_jwt_format
- Update test_validate_api_key_valid to use JWT format keys
- Fix test assertions for error message matching

Documentation:
- Create comprehensive MINIMAX_INTEGRATION.md guide (380+ lines)
- Update MULTI_LLM_SUPPORT.md with MiniMax platform entry
- Update 01-installation.md extras table
- Update INTEGRATIONS.md AI platforms table
- Update AGENTS.md adaptor import pattern example
- Fix README.md platform count from 4 to 5

All tests pass (33 passed, 3 skipped)
Lint checks pass

Co-authored-by: octo-patch <octo-patch@users.noreply.github.com>

* fix: improve MiniMax adaptor — typed exceptions, key validation, tests, docs

- Remove invalid "minimax" self-reference from all-llms dependency group
- Use typed OpenAI exceptions (APITimeoutError, APIConnectionError)
  instead of string-matching on generic Exception
- Replace incorrect JWT assumption in validate_api_key with length check
- Use DEFAULT_API_ENDPOINT constant instead of hardcoded URLs (3 sites)
- Add Path() cast for output_path before .is_dir() call
- Add sys.modules mock to test_enhance_missing_library
- Add mocked test_enhance_success with backup/content verification
- Update test assertions for new exception types and key validation
- Add MiniMax to __init__.py docstrings (module, get_adaptor, list_platforms)
- Add MiniMax sections to MULTI_LLM_SUPPORT.md (install, format, API key,
  workflow example, export-to-all)

Follows up on PR #318 by @octo-patch (feat: add MiniMax AI as LLM platform adaptor).

Co-Authored-By: Octopus <octo-patch@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: octo-patch <octo-patch@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

uv.lock

@@ -5699,7 +5699,7 @@ wheels = [
 
 [[package]]
 name = "skill-seekers"
-version = "3.2.0"
+version = "3.3.0"
 source = { editable = "." }
 dependencies = [
     { name = "anthropic" },
@@ -5816,6 +5816,9 @@ mcp = [
     { name = "starlette" },
     { name = "uvicorn" },
 ]
+minimax = [
+    { name = "openai" },
+]
 notion = [
     { name = "notion-client" },
 ]
@@ -5930,6 +5933,7 @@ requires-dist = [
     { name = "numpy", marker = "extra == 'embedding'", specifier = ">=1.24.0" },
     { name = "openai", marker = "extra == 'all'", specifier = ">=1.0.0" },
     { name = "openai", marker = "extra == 'all-llms'", specifier = ">=1.0.0" },
+    { name = "openai", marker = "extra == 'minimax'", specifier = ">=1.0.0" },
     { name = "openai", marker = "extra == 'openai'", specifier = ">=1.0.0" },
     { name = "opencv-python-headless", marker = "extra == 'video-full'", specifier = ">=4.9.0" },
     { name = "pathspec", specifier = ">=0.12.1" },
@@ -5978,7 +5982,7 @@ requires-dist = [
     { name = "yt-dlp", marker = "extra == 'video'", specifier = ">=2024.12.0" },
     { name = "yt-dlp", marker = "extra == 'video-full'", specifier = ">=2024.12.0" },
 ]
-provides-extras = ["mcp", "gemini", "openai", "all-llms", "s3", "gcs", "azure", "docx", "epub", "video", "video-full", "chroma", "weaviate", "sentence-transformers", "pinecone", "rag-upload", "all-cloud", "jupyter", "asciidoc", "pptx", "confluence", "notion", "rss", "chat", "embedding", "all"]
+provides-extras = ["mcp", "gemini", "openai", "minimax", "all-llms", "s3", "gcs", "azure", "docx", "epub", "video", "video-full", "chroma", "weaviate", "sentence-transformers", "pinecone", "rag-upload", "all-cloud", "jupyter", "asciidoc", "pptx", "confluence", "notion", "rss", "chat", "embedding", "all"]
 
 [package.metadata.requires-dev]
 dev = [