feat: include reply/quote context in Claude prompt

[timurvafin]

Summary

When a user replies to a message (especially with a highlighted fragment — Telegram's partial-quote feature, Bot API 7.0+), the bot was reading only update.message.text and dropping the quoted context. Claude then had to guess what the user was referring to.

This PR extracts the quoted fragment and prepends it to the user's new text as a markdown blockquote, so Claude sees both the fragment and the response in a single prompt.

Before vs after

Before:

User (replying with quote on Claude's earlier message): "а каково его население?"
  → prompt sent to Claude: "а каково его население?"
  → Claude: "its what? please clarify"

After:

User (replying with quote on "Столица Франции — Париж."): "а каково его население?"
  → prompt sent to Claude:
    > Столица Франции — Париж.

    а каково его население?
  → Claude: "Население Парижа — около 2,1 млн человек…"

Design

• Priority: message.quote.text (partial quote, Bot API 7.0+) wins over the full reply_to_message.text. If the user highlighted a fragment, that's what they mean.
• Fallback: If there's no partial quote, use the full replied-to message. If that message is media, use its caption.
• Format: markdown blockquote (> line\n> line\n\ntext), natural for Claude.
• No changes when there's no reply/quote — behaviour is identical.
• Shared helper in src/bot/utils/quote_prompt.py — both agentic_text and classic handle_text go through it, so classic mode gets the feature for free.

Changes

• src/bot/utils/quote_prompt.py — new build_user_prompt(message) -> str helper with priority logic and markdown-blockquote rendering.
• src/bot/orchestrator.py — agentic_text uses build_user_prompt(update.message) instead of update.message.text.
• src/bot/handlers/message.py — handle_text_message (classic) same wiring; .pdf unaffected.
• tests/unit/test_bot/test_quote_prompt.py — 10 tests: plain/reply/partial-quote priority/multiline/media-caption/edge cases (no-text, no-reply, empty user text).

Live verification

Reply via Telegram client with highlighted fragment of Claude's previous answer; bot's database prompt now includes the blockquote; Claude's reply is contextually correct.

Test plan

• make test — 540 passed (10 new)
• black/isort/flake8 clean
• Live smoke: replied to a bot message with a follow-up question whose only referent was the quoted fragment. Claude resolved the reference correctly.

🤖 Generated with Claude Code