docs: Update documentation for v1.0 release (#476)

* docs: Update documentation for v1.0 release

- Integrate breaking changes naturally without alarming users
- Replace deprecated inputs (direct_prompt, custom_instructions, mode) with new unified approach
- Update all examples to use prompt and claude_args instead of deprecated inputs
- Add migration guides to help users transition from v0.x to v1.0
- Emphasize automatic mode detection as a key feature
- Update all workflow examples to @v1 from @beta
- Document how claude_args provides direct CLI control
- Update FAQ with automatic mode detection explanation
- Convert all tool configuration to use claude_args format

* fix: Apply prettier formatting to documentation files

* fix: Update all Claude model versions to latest and improve documentation accuracy

- Update all model references to claude-4-0-sonnet-20250805 (latest Sonnet 4)
- Update Bedrock models to anthropic.claude-4-0-sonnet-20250805-v1:0
- Update Vertex models to claude-4-0-sonnet@20250805
- Fix cloud-providers.md to use claude_args instead of deprecated model input
- Ensure all examples use @v1 instead of @beta
- Keep claude-opus-4-1-20250805 in examples where Opus is demonstrated
- Align all documentation with v1.0 patterns consistently

* feat: Add dedicated migration guide as requested in PR feedback

- Create comprehensive migration-guide.md with step-by-step instructions
- Add prominent links to migration guide in README.md
- Update usage.md to reference the separate migration guide
- Include before/after examples for all common scenarios
- Add checklist for systematic migration
- Address Ashwin's feedback about having a separate, clearly linked migration guide

docs/cloud-providers.md

@@ -20,23 +20,25 @@ Use provider-specific model names based on your chosen provider:
 
 ```yaml
 # For direct Anthropic API (default)
-- uses: anthropics/claude-code-action@beta
+- uses: anthropics/claude-code-action@v1
   with:
     anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
     # ... other inputs
 
 # For Amazon Bedrock with OIDC
-- uses: anthropics/claude-code-action@beta
+- uses: anthropics/claude-code-action@v1
   with:
-    model: "anthropic.claude-3-7-sonnet-20250219-beta:0" # Cross-region inference
     use_bedrock: "true"
+    claude_args: |
+      --model anthropic.claude-4-0-sonnet-20250805-v1:0
     # ... other inputs
 
 # For Google Vertex AI with OIDC
-- uses: anthropics/claude-code-action@beta
+- uses: anthropics/claude-code-action@v1
   with:
-    model: "claude-3-7-sonnet@20250219"
     use_vertex: "true"
+    claude_args: |
+      --model claude-4-0-sonnet@20250805
     # ... other inputs
 ```
 
@@ -59,10 +61,11 @@ Both AWS Bedrock and GCP Vertex AI require OIDC authentication.
     app-id: ${{ secrets.APP_ID }}
     private-key: ${{ secrets.APP_PRIVATE_KEY }}
 
-- uses: anthropics/claude-code-action@beta
+- uses: anthropics/claude-code-action@v1
   with:
-    model: "anthropic.claude-3-7-sonnet-20250219-beta:0"
     use_bedrock: "true"
+    claude_args: |
+      --model anthropic.claude-4-0-sonnet-20250805-v1:0
     # ... other inputs
 
   permissions:
@@ -84,10 +87,11 @@ Both AWS Bedrock and GCP Vertex AI require OIDC authentication.
     app-id: ${{ secrets.APP_ID }}
     private-key: ${{ secrets.APP_PRIVATE_KEY }}
 
-- uses: anthropics/claude-code-action@beta
+- uses: anthropics/claude-code-action@v1
   with:
-    model: "claude-3-7-sonnet@20250219"
     use_vertex: "true"
+    claude_args: |
+      --model claude-4-0-sonnet@20250805
     # ... other inputs
 
   permissions: