fix: correct GitHub Copilot instructions and Kiro CLI rule-details path resolution (#82, #84) (#87)

* fix: correct GitHub Copilot setup instructions (#82)

Replace incorrect .copilot/instructions.md and COPILOT.md setup with
the officially supported .github/copilot-instructions.md approach, which
is auto-detected by VS Code and applied to all chat requests.

- Remove Option 1 (.copilot/ directory) and Option 2 (COPILOT.md)
- Add setup using .github/copilot-instructions.md per VS Code docs
- Update troubleshooting tips for GitHub Copilot
- Update version control recommendations to match new paths

* fix: place rule details inside steering directory for Kiro CLI (#84)

Kiro CLI resolves relative paths from the steering file location, not
the project root. Move .aidlc-rule-details/ into
.kiro/steering/aws-aidlc-rules/ so that references in core-workflow.md
resolve correctly without modifying the shared workflow file.

- Update Kiro CLI setup commands for all platforms
- Update directory structure diagram
- Add explanatory note about Kiro CLI path resolution
- Add troubleshooting tip for rule details placement

* fix: restore platform-specific fallback paths for rule details loading (#84)

Kiro CLI resolves relative paths in steering files relative to the
steering file location, not the workspace root. The consolidation to a
single .aidlc-rule-details/ path caused Kiro CLI to look for rule
details at .kiro/steering/aws-aidlc-rules/.aidlc-rule-details/, which
does not exist.

Restore the original fallback path order so the agent checks these
paths and uses the first one found:
- .aidlc-rule-details/ (Cursor, Cline, Claude Code, GitHub Copilot)
- .kiro/aws-aidlc-rule-details/ (Kiro IDE and CLI)
- .amazonq/aws-aidlc-rule-details/ (Amazon Q Developer)

Author: harmjeff