agency: deep-link glued to card + label adapts to spawn-topic mode

[MagMueller]

Two UX wins on the spawn-topic flow.

1. Default-button labels reflect routing

Before: `✅ Yes` / `⏭ Skip` / `✏️ Edit` regardless of whether `--spawn-topic` was set. From the button alone you couldn't tell if tapping would run in-place or fork a topic.

After:

• `--spawn-topic` OFF → `✅ Yes` / `⏭ Skip` / `✏️ Edit`
• `--spawn-topic` ON → `🧵 Yes (new thread)` / `⏭ Skip` / `🧵 Edit (new thread)`

`agency-report` picks the variant at post time from `args.spawn_topic`.

2. Deep-link to the spawned topic is glued to the card

Before: when Yes/Edit spawned a fresh forum topic, the bot posted a separate "→ working in X" reply under the card with a `🧵 Open thread` URL-button. That reply got buried as more cards landed in the topic — by the time you scrolled back to the card, the link was several screens away.

After: the URL-button row gets appended to the card's own `inline_keyboard`. It scrolls with the card. You can jump to the worker topic from the card itself, even weeks later.

`_agency_mark_picked` grows an `append_url_row` parameter. It also strips any prior trailing URL-only rows before re-applying so the deep-link doesn't accumulate across re-taps. Re-applied on every tap so the link survives mid-mind-changes.

3. Multi-tap dedupes the worker thread

Tapping Yes twice no longer creates two topics. The first tap sets `worker_topic_id` in agency.db; subsequent action/refine taps reuse it and re-dispatch into the same thread. The URL-row on the card always points at that one worker topic.

Refactor

The worker-topic resolution moved before the keyboard mark in `_handle_agency_callback` so we know `new_thread_id` when computing the URL row to glue. The previous "mark first → spawn → reply with URL" ordering is replaced with "resolve-thread → mark with URL row → dispatch".

The standalone URL-reply block at the bottom of the action/refine handler is dropped — superseded by the on-card row.

Test plan

• `agency-report --spawn-topic` posts a card with the `🧵 Yes (new thread)` label
• `agency-report` (no flag) posts a card with the `✅ Yes` label
• Tap Yes on a `--spawn-topic` card → fresh topic spawns AND a `🧵 Open thread` URL row appears as the last keyboard row
• Re-tap Yes on the same card → no new topic; URL row keeps pointing to the same one
• Tap Skip then Yes → URL row still points to the original spawned topic (Skip preserves `worker_topic_id`)
• Tap a card with no `--spawn-topic` → no URL row appears (work runs in-place)

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Summary by cubic

Makes the spawn-topic flow clearer and easier to navigate. Buttons now show if they fork a thread, and the deep-link to that thread stays attached to the card. Also prevents duplicate threads on multi-tap.

• New Features

  • Button labels adapt to --spawn-topic at post time:
    • Off → ✅ Yes / ⏭ Skip / ✏️ Edit
    • On → 🧵 Yes (new thread) / ⏭ Skip / 🧵 Edit (new thread)
  • When a new thread is spawned, a "🧵 Open thread" URL row is added to the card’s inline_keyboard so the link scrolls with the card.
  • Multi-tap reuses the same worker thread via worker_topic_id; no duplicate topics.

• Refactors

  • Resolve or create the worker thread before marking the keyboard; then mark (with optional URL row) and dispatch.
  • Removed the separate "→ working in X" reply; _agency_mark_picked now accepts append_url_row and cleans trailing URL-only rows to avoid duplicates.

^{Written for commit 7998a64. Summary will update on new commits.}