refactor: complete v1.0 simplification by removing all legacy inputs

- Remove all backward compatibility for v1.0 simplification
- Remove 10 legacy inputs from base-action/action.yml
- Remove 9 legacy inputs from main action.yml
- Simplify ClaudeOptions type to just timeoutMinutes and claudeArgs
- Remove all legacy option handling from prepareRunConfig
- Update tests to remove references to deleted fields
- Remove obsolete test file github/context.test.ts
- Clean up types to remove customInstructions, allowedTools, disallowedTools

Users now use claudeArgs exclusively for CLI control.

base-action/action.yml

@@ -14,47 +14,10 @@ inputs:
     description: "Path to a file containing the prompt to send to Claude Code (mutually exclusive with prompt)"
     required: false
     default: ""
-  allowed_tools:
-    description: "Comma-separated list of allowed tools for Claude Code to use"
-    required: false
-    default: ""
-  disallowed_tools:
-    description: "Comma-separated list of disallowed tools that Claude Code cannot use"
-    required: false
-    default: ""
-  max_turns:
-    description: "Maximum number of conversation turns (default: no limit)"
-    required: false
-    default: ""
-  mcp_config:
-    description: "MCP configuration as JSON string or path to MCP configuration JSON file"
-    required: false
-    default: ""
   settings:
     description: "Claude Code settings as JSON string or path to settings JSON file"
     required: false
     default: ""
-  system_prompt:
-    description: "Override system prompt"
-    required: false
-    default: ""
-  append_system_prompt:
-    description: "Append to system prompt"
-    required: false
-    default: ""
-  model:
-    description: "Model to use (provider-specific format required for Bedrock/Vertex)"
-    required: false
-  anthropic_model:
-    description: "DEPRECATED: Use 'model' instead. Model to use (provider-specific format required for Bedrock/Vertex)"
-    required: false
-  fallback_model:
-    description: "Enable automatic fallback to specified model when default model is unavailable"
-    required: false
-  claude_env:
-    description: "Custom environment variables to pass to Claude Code execution (YAML multiline format)"
-    required: false
-    default: ""
 
   # Action settings
   timeout_minutes:
@@ -137,19 +100,11 @@ runs:
       env:
         # Model configuration
         CLAUDE_CODE_ACTION: "1"
-        ANTHROPIC_MODEL: ${{ inputs.model || inputs.anthropic_model }}
         INPUT_PROMPT: ${{ inputs.prompt }}
         INPUT_PROMPT_FILE: ${{ inputs.prompt_file }}
-        INPUT_ALLOWED_TOOLS: ${{ inputs.allowed_tools }}
-        INPUT_DISALLOWED_TOOLS: ${{ inputs.disallowed_tools }}
-        INPUT_MAX_TURNS: ${{ inputs.max_turns }}
-        INPUT_MCP_CONFIG: ${{ inputs.mcp_config }}
         INPUT_SETTINGS: ${{ inputs.settings }}
-        INPUT_SYSTEM_PROMPT: ${{ inputs.system_prompt }}
-        INPUT_APPEND_SYSTEM_PROMPT: ${{ inputs.append_system_prompt }}
         INPUT_TIMEOUT_MINUTES: ${{ inputs.timeout_minutes }}
-        INPUT_CLAUDE_ENV: ${{ inputs.claude_env }}
-        INPUT_FALLBACK_MODEL: ${{ inputs.fallback_model }}
+        INPUT_CLAUDE_ARGS: ${{ inputs.claude_args }}
         INPUT_EXPERIMENTAL_SLASH_COMMANDS_DIR: ${{ inputs.experimental_slash_commands_dir }}
 
         # Provider configuration