refactor: restore root layout and split mysql config

docs/device-mapper.md

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+# Device Mapper Usage
+
+This tool builds a cross-platform lookup index from `workspace/brands/*.md`.
+
+## 1) Build index
+
+```bash
+python3 tools/device_mapper.py build
+```
+
+Output file: `dist/device_index.json`
+
+## 2) Query from command line
+
+```bash
+python3 tools/device_mapper.py find --name 'iPhone14,5' --brand Apple
+python3 tools/device_mapper.py find --name 'M2102J2SC' --brand Xiaomi
+python3 tools/device_mapper.py find --name 'L55M5-AD' --brand Xiaomi
+```
+
+## 3) JSON structure
+
+- `records`: normalized device records
+  - `device_name`: standard marketing name
+  - `brand`: normalized brand
+  - `manufacturer_brand`: manufacturer-level brand
+  - `market_brand`: market sub-brand
+  - `device_type`: `phone | tablet | wear | tv | other`
+  - `aliases`: all searchable aliases
+- `lookup`: normalized alias -> candidate `record.id[]`
+- `brand_aliases`: normalized brand aliases to filter by app-provided brand
+- `brand_management`: brand governance metadata
+
+## 4) App-side integration
+
+1. Load `dist/device_index.json` into memory.
+2. Normalize input `name` and optional `brand`.
+3. Use `lookup[normalized_name]` to fetch candidate records.
+4. Normalize brand via `brand_management`.
+5. Filter records by normalized manufacturer or market brand when needed.
+6. Return first candidate or all candidates.
+
+Normalization rule:
+
+- lower-case
+- keep only `[0-9a-z\u4e00-\u9fff]`
+- remove spaces, hyphens, underscores and punctuation
+
+## 5) Device type mapping
+
+Supported categories:
+
+- `phone`
+- `tablet`
+- `wear`
+- `tv`
+- `other`