Add app analyzing/debugging docs and scripts (#174)

scripts/http-diff/README.md

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+# HTTP Body Diff Tool
+
+This tool extracts and compares response bodies from two `.http` files.
+It supports XML and JSON normalization (pretty-printing) and automatically masks common "noisy" fields like timestamps to make actual differences easier to spot.
+
+## Usage
+
+```bash
+go run scripts/http-diff/main.go <path/to/file1.http> <path/to/file2.http>
+```
+
+To generate a side-by-side HTML report:
+
+```bash
+go run scripts/http-diff/main.go --html report.html <path/to/file1.http> <path/to/file2.http>
+```
+
+## Features
+
+- **Body Extraction**: Automatically finds the response body within the `/* ... */` comment block at the end of the file.
+- **Side-by-Side View**: Generates an HTML report with a clear side-by-side comparison.
+- **Normalization**:
+  - Pretty-prints XML and JSON.
+  - Trims whitespace from XML character data.
+- **Noise Reduction**:
+  - Automatically replaces ISO 8601 timestamps with `[TIMESTAMP]`.
+  - Masks specific XML tags: `<updatedOn>`, `<createdOn>`, `<lastModified>`, `<timestamp>`.
+  - Masks specific JSON keys: `timestamp`, `updatedOn`, `createdOn`, `expires_at`.
+- **Diff Output**:
+  - Displays a line-by-line diff.
+  - Show context for unchanged parts (first and last two lines, with `...` in between).
+  - Uses `+` for additions and `-` for deletions.