feat: import Decent Espresso profiles via DecentConverter

[hessius]

Summary

Port the DecentConverter logic from the met-community-profiles repository to enable importing Decent Espresso profiles into Meticulous format. This extends the existing "Import from URL" feature (#96) and addresses profile interoperability (#284).

Background

Decent Espresso is the most popular prosumer espresso platform with thousands of community-shared profiles. The MeticulousHome team built a DecentConverter (Vue component) that converts Decent .json profiles to Meticulous format. We should port this logic to our backend.

Behaviour

Import Flow

1. User navigates to Profile Catalogue → Import
2. Three import options:
   • From file (existing) — upload .json file
   • From URL (existing, Import from link #96) — paste any URL
   • From Decent (new) — paste a Decent profile URL or upload Decent .json
3. For Decent import:
   • Backend detects Decent format (has author, beverage_type, steps[] with flow/pressure targets)
   • Runs DecentConverter logic to translate:
     • Decent steps[] → Meticulous stages[]
     • Decent flow/pressure targets → Meticulous dynamics
     • Decent exit_condition → Meticulous exit_triggers
     • Decent temperature → Meticulous temperature
     • Decent notes → Meticulous description
   • Shows preview of converted profile with stage visualization
   • User confirms → profile saved

Decent Profile Sources

• Decent community links: https://visualizer.coffee/shots/... export URLs
• Diaspora profiles: Various community forums share .json exports
• Direct file upload: Users export from Decent tablet app

Conversion Details (from DecentConverter.vue)

Decent	Meticulous
steps[].flow	stages[].dynamics.points (flow type)
steps[].pressure	stages[].dynamics.points (pressure type)
steps[].temperature	stages[].temperature
steps[].exit.type == "pressure_over"	exit_triggers[].type = "pressure"
steps[].exit.type == "flow_over"	exit_triggers[].type = "flow"
steps[].seconds	exit_triggers[].type = "time"
steps[].weight	exit_triggers[].type = "weight"
author	profile.author
title	profile.name
notes	profile.description

Edge Cases

• Profiles with advanced Decent features (move-on conditions, limiter) → best-effort conversion with warning
• Profiles with espresso_decline step type → map to declining pressure/flow dynamics
• Invalid/corrupt files → clear error message with format guidance

Implementation

Backend

1. New service: apps/server/services/decent_converter.py
   • detect_decent_format(data: dict) -> bool
   • convert_decent_to_meticulous(data: dict) -> dict
   • Port logic from DecentConverter.vue to Python
2. Extend POST /api/import-from-url to auto-detect Decent format
3. New endpoint: POST /api/convert-decent for direct file conversion
4. Validate output against espresso-profile-schema

Frontend

1. Add "Decent" import option in ProfileCatalogue import dialog
2. Show conversion preview before saving
3. Display warnings for unsupported Decent features
4. i18n keys for all Decent-specific strings (6 locales)

Acceptance Criteria

• Decent profiles auto-detected by format
• Conversion produces valid Meticulous profiles (passes schema validation)
• Temperature, flow, pressure, and weight targets correctly mapped
• Exit conditions correctly translated
• Preview shown before save
• Edge cases handled with user-visible warnings
• i18n for all 6 locales
• Tests for converter with sample Decent profiles

References

• Research: research: MeticulousHome repository analysis — findings & impact for milestones 2.2–2.4 #283
• Import from URL: Import from link #96
• Profile interop: feat: Decent Espresso profile import & URL link conversion #284
• DecentConverter source: met-community-profiles
• Decent profile format: Decent docs
• Meticulous profile schema: espresso-profile-schema