chore: add prompt sync workflow rule

Documents that prompts exist in two repos (Talk-Flow + talkis-proxy)
and must be kept in sync when modified.

.agent/workflows/update-prompts.md

@@ -0,0 +1,54 @@
+---
+description: How to update transcription prompts (styles, languages, overrides) — must sync both repos
+---
+
+# Updating Transcription Prompts
+
+Prompts are stored in **two locations** and must be kept in sync:
+
+1. **Client (Tauri app):** `Talk-Flow/src/config/transcription-prompts/`
+   - Used when the user provides their own API key
+   - Loaded by Rust backend (`prompt_config.rs`)
+
+2. **Server (Go proxy):** `talkis-proxy/internal/prompt/prompts/`
+   - Used for subscription users (proxied through the Go service)
+   - Embedded into the Go binary via `embed.FS`
+
+## Steps to update prompts
+
+1. **Make your changes** in `Talk-Flow/src/config/transcription-prompts/`
+2. **Copy all changed files** to the proxy:
+   ```bash
+   cp -r /Volumes/KINGSTON/project/talkflow/Talk-Flow/src/config/transcription-prompts/* \
+         /Volumes/KINGSTON/project/talkflow/talkis-proxy/internal/prompt/prompts/
+   ```
+3. **Verify the Go build** still compiles:
+   ```bash
+   cd /Volumes/KINGSTON/project/talkflow/talkis-proxy && go build ./...
+   ```
+4. **Commit in both repositories**
+
+## File structure
+
+```
+manifest.json          — registry of all languages, styles, overrides
+base/common.json       — core rules (shared across all styles)
+languages/default.json — fallback language config
+languages/ru.json      — Russian language rules + filler words
+languages/en.json      — English language rules
+styles/classic.json    — Классический style
+styles/business.json   — Деловой style
+styles/tech.json       — Разработка style
+overrides/ru.classic.json  — Russian × Classic overrides
+overrides/ru.business.json — Russian × Business overrides
+overrides/ru.tech.json     — Russian × Tech overrides
+```
+
+## Adding a new style
+
+1. Create `styles/newstyle.json` with `promptTitle`, `rules`, `temperature`, `examples`
+2. Add entry to `manifest.json` under `styles` and `styleOrder`
+3. Optionally create `overrides/ru.newstyle.json` for language-specific overrides
+4. Add the override key to `manifest.json` under `overrides`
+5. Update the UI dropdown in `SettingsTabs.tsx` (Tauri app)
+6. **Copy to proxy repo** (step 2 above)