[ainyan03]

Summary

Adds the user-exposed connectors (headers, sockets, HAT buses, Grove ports, Proto pads, expansion FPC/BTB connectors) and links to the official product pages and schematics to the board specification catalog.

The main purpose is to make the existing validation rule complete: a pin that users can reach through a connector must not be used as an invariant detection class (E_DETECT_CLASS_CONNECTOR). Until now only Port A, M-Bus and a few other ports were described, so most exposed pins were not protected by that rule.

• One commit per family: StopWatch, Atom, Stick, Stamp, Core, Paper, and the remaining boards, plus commits for product names and connector groups.
• Every terminal-to-GPIO mapping was taken from the official pin tables, PinMap images or schematics. Values that could not be confirmed were left out rather than guessed. Where official sources disagree, the catalog note states which source was followed.
• The schema now allows one connector position to reach several GPIOs (e.g. StickC Plus HAT pin 4 = GPIO36/GPIO25), and connector types whose physical pitch is not documented (pitch_mm: null, logical numbering only).
• Port names port_a..port_e keep their meaning as the M5Unified pin-table contract. Physical ports without a pin-table entry use separate names (e.g. StamPLC grove_c, Station grove_a2), and ports that belong to a base or sub-board stay in the accessory definitions.
• Product names (official_name) were checked against the official product page titles; matching names are marked official_name_verified, and differing spellings were corrected. Entries that describe several products (Basic/Gray/Fire, Station Bat/485) or a module sold inside a set (Atom PSRAM) are left unverified.
• Optional connector.group marks separate sockets that form one physical set (Atom bottom headers, StopWatch rear sockets, Stamp pin rows) so tools can show them together. Each socket keeps its own terminal numbering and first pin.
• Generated C++ (src/board_detect/m5/generated/) is unchanged.

Not covered

• USB connectors, battery connectors, antennas, internal test pads, and terminals that are not directly connected to a GPIO (isolated inputs, relay contacts, CAN/RS485 terminal blocks).
• Boards whose official documentation is not yet available are unchanged.

Testing

• extras/board_spec: npm test (216 tests, also with M5Unified absent) and npm run check at every commit.
• Each family was cross-checked against the official sources independently of the edit.