docs: add link checker CI and improve CHANGELOG v3.0.0 migration guide

- Add .github/workflows/docs-check.yml for automated link checking
  - Uses lychee-action for Markdown link validation
  - Includes markdownlint for format checking
  - Auto-creates issues on link check failures
- Enhance CHANGELOG v3.0.0 Breaking Changes section
  - Add migration script for Loop ID format change (4→5 digits)
  - Document impact scope (Loop files, ShadowGrandDigest, last_digest_times.json)
  - Clarify user impact for each breaking change

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: web-flow

.github/workflows/docs-check.yml

@@ -0,0 +1,73 @@
+name: Documentation Check
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - '**/*.md'
+  pull_request:
+    branches: [main]
+    paths:
+      - '**/*.md'
+
+jobs:
+  link-check:
+    name: Check Markdown Links
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Link Checker
+        uses: lycheeverse/lychee-action@v1
+        with:
+          args: >-
+            --verbose
+            --no-progress
+            --exclude-mail
+            --exclude 'https://github.com/Bizuayeu/Plugins-Weave/compare/*'
+            --exclude 'https://github.com/Bizuayeu/Plugins-Weave/releases/*'
+            '**/*.md'
+          fail: true
+
+      - name: Create Issue on Failure
+        if: failure()
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const title = 'Documentation Link Check Failed';
+            const body = `The documentation link check has failed in workflow run [#${context.runNumber}](${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}).
+
+            Please review the broken links and fix them.`;
+
+            // Check if issue already exists
+            const issues = await github.rest.issues.listForRepo({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'open',
+              labels: 'documentation'
+            });
+
+            const existingIssue = issues.data.find(issue => issue.title === title);
+
+            if (!existingIssue) {
+              await github.rest.issues.create({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                title: title,
+                body: body,
+                labels: ['documentation', 'bug']
+              });
+            }
+
+  markdown-lint:
+    name: Lint Markdown Files
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: markdownlint-cli2-action
+        uses: DavidAnson/markdownlint-cli2-action@v16
+        with:
+          globs: '**/*.md'
+          fix: false
+        continue-on-error: true

EpisodicRAG/CHANGELOG.md

@@ -11,9 +11,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking Changes
 
-- **Loop IDの桁数変更**: 4桁→5桁（例: `Loop0001` → `L00001`）
+- **Loop IDの桁数変更**: 4桁→5桁
+  - 旧形式: `Loop0001`
+  - 新形式: `L00001`
+  - **移行方法**: 既存Loopファイルのリネームが必要
+    ```bash
+    # 例: L0001_xxx.txt → L00001_xxx.txt
+    cd your_loops_directory
+    for f in L[0-9][0-9][0-9][0-9]_*.txt; do
+      mv "$f" "L0${f:1}"
+    done
+    ```
+  - **影響範囲**:
+    - Loopファイル名
+    - ShadowGrandDigest.txt 内の `source_files` 参照
+    - last_digest_times.json 内の参照
+
 - **ドキュメントの完全SSoT化**: 用語定義はREADME.mdに一元化
+  - ユーザーへの影響なし（ドキュメント構造の改善のみ）
+
 - **テストスイートの導入**: pytest + hypothesis によるプロパティベーステスト
+  - 開発者向け変更、エンドユーザーへの影響なし
 
 ### Changed