[chore](docs): update commit message guidelines and remove old file

COMMIT_MESSAGE.md

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+## Commit Message Requirements
+
+- A commit message consists of a **title** and an optional **body**.
+
+### 1. Commit Title Format
+
+- The commit title must follow this format:
+
+  ```text
+  [type] short summary of main change [BREAK]
+  ```
+
+- `type` is enclosed in square brackets (`[` `]`) and describes the nature of the change. For example:
+
+    - `[feature]` : new feature
+    - `[fix]` : bug fix
+    - `[docs]` : documentation changes
+    - `[refactor]` : refactoring without behavior change
+    - `[test]` : tests added or updated
+    - `[chore]` : build, config, or other maintenance tasks
+
+- You may introduce additional types if needed, following the same `[type]` pattern.
+- The text after the type is a **concise, one-line summary of the most important change**.
+- Keep the title **under 72 characters**.
+- Use **present tense** in the title.
+    - e.g. `add`, `fix`, `update`, `refactor` (not `added`, `fixed`)
+
+### 2. BREAK Suffix
+
+- If the commit introduces a **breaking change** (for example, variable renames, API signature changes, or anything that breaks backward compatibility), add the `[BREAK]` suffix at the end of the title.
+
+  ```text
+  [feature] add new auth middleware [BREAK]
+  [refactor] rename core config struct [BREAK]
+  ```
+
+- If there is no breaking change, do **not** add `[BREAK]`.
+
+### 3. Commit Body
+
+- The commit body should **briefly describe the key changes in the edited files**.
+- A bullet list is recommended:
+
+  ```text
+  - describe change 1
+  - describe change 2
+  - summarize changes per file or module
+  ```
+
+- Focus on **what changed and why**, rather than low-level implementation details.
+- If there are security or privacy-related changes, explicitly mention them.
+
+### 4. Examples
+
+- Without breaking changes:
+
+  ```text
+  [feature] add support for local proxy client
+
+  - add CLI flags for local proxy configuration
+  - implement basic request forwarding logic
+  - update documentation with usage examples
+  ```
+
+- With breaking changes (e.g., renaming variables or structures):
+
+  ```text
+  [refactor] rename db config fields for clarity [BREAK]
+
+  - rename DSN to DatabaseURL in the config struct
+  - update all references in store and CLI packages
+  - adjust environment variable parsing logic
+  ```
+
+This guideline preserves the original project’s requirements (present tense, short main-change summary, explicit BREAK marking) while adapting the format to use `[type]` commit prefixes.