feat: Phase 4 — Telegram interactive approval bot

[constgemm]

The propose-then-approve gate, moved from the terminal (--commit) to your phone.

Flow

For each new candidate not contradicted by Dawarich, telegram.py:

1. sends a card showing every field — missing ones flagged ⚠ missing — with an inline ✅ Approve / ⏭ Skip keyboard;
2. waits for your tap (long-poll getUpdates, so the container needs no inbound port);
3. on Approve, writes the flight to AirTrail and replies "✅ Wrote LX1246 LSZH->ESSA … AirTrail now has N flights.";
4. on Skip or timeout, writes nothing.

Robustness

• callback_data is namespaced (lay:ok:<idx>) so taps from other bots in the chat are ignored; decisions are buffered by index so out-of-order/duplicate taps aren't lost.
• Priming drains stale updates so an old tap can't leak into a fresh run.
• A write failure is reported in-chat, never raised.
• All Telegram HTTP and AirTrail post/fetch are injectable → fully tested offline.

Changes

• telegram.py — config, Bot API transport, card rendering, approval session, run_approvals.
• populate.py — opt-in step (TELEGRAM_APPROVE=1 or --telegram-approve).
• Dockerfile, .env.example, README.
• tests/test_telegram.py — 10 tests. Suite on this branch: 39 green.

Touches the same populate.py import block + main() as PRs #7/#8 — trivial conflict resolve on whichever merges later.

Needs from you: a bot token from @Botfather + your chat id (→ .env / infra-secrets, never committed). The token is a secret — keep it out of the vault.

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