Adds full SRAM AXS support alongside the existing Shimano Di2 path, plus a user-facing way to correct the detected groupset and faster replay speeds. Highlights Groupset auto-detection

Two-layer detection in extension/src/gear-parser.js:
    FIT device metadata — manufacturer ID + product_name/device_name keyword match (shimano, di2, dura-ace, sram, axs, etap, campagnolo, eps, fsa we, …)
    Observed gear signature — heuristics on chainring/cassette teeth (10T smallest cog ⇒ SRAM AXS; 11-12-13-14-15-17-19-21-24-27-30-34 ⇒ Shimano 12s; 48/35 ⇒ SRAM; 50/34 ⇒ Shimano)
Successfully tested end-to-end with Shimano Di2 and SRAM AXS FIT files

Groupset override (Debug panel)

New Override groupset dropdown + Re-analyse button in the floating Debug panel
~13 popular presets (Shimano 2×11/2×12, SRAM AXS 2×12, SRAM XPLR 1×12/1×13, Shimano GRX 1×11, …) plus Detected from ride data
Re-runs shift score, gear-usage stats, cross-chain detection, optimal-gear suggestions and any zoomed section scores against the chosen drivetrain

Playback

Added 40×, 60×, 100× speed buttons to replay controls

UI cleanup

Removed drivetrain animation and shifting-analysis box from the replay panel
Fixed CSS brace bug that was breaking gear-usage card rendering in dark mode

Documentation

New README section explaining groupset auto-detection logic, why it can be wrong, and how to override it
Marked the standalone web app as deprecated — all active development is on the browser extension
Refreshed main plugin screenshot; added di2va-groupset-detection.png

Tested

Shimano Di2 (2×11, 2×12)
SRAM AXS (road and XPLR)

Campagnolo EPS / FSA WE detection logic is in place but not yet verified against real-world FIT files.