fix(embedded-agent): honor provider pick, survive reload, persist agent pins (v0.4.1)

[kurtstohrer]

Summary

Reliability fixes for embedded agent mode, cut as v0.4.1.

Fixed

• The selected provider actually applies the task. Built-in personas hard-coded claude-local, so every apply/seed run spawned claude regardless of the provider chosen in Settings → Providers — surfacing as spawn claude ENOENT when claude wasn't installed (e.g. Copilot was selected). Built-in personas now inherit the global active provider; an explicit per-persona pin in .annotask/agents.json still wins (resolveProviderForTaskType).
• Per-agent provider/model pins persist. Setting a persona's model in Settings → Agents was silently wiped whenever the provider's live model catalog couldn't be enumerated (Copilot's interactive-only picker), and a saved value displayed empty. The field now keeps + shows the saved value; a stale id from a different provider is cleared on provider change instead, never on catalog-fetch failure.
• Reloading the page no longer destroys an in-flight apply. The spawn server keeps a task-bearing run alive across a client disconnect (detach grace) and finalizes the task on the child's own exit (clean → review, interrupted/failed → pending). The client no longer reverts the task on pagehide and warns before an accidental reload. A stale orphan-finalize can't clobber a newer run for the same task.
• Auto-run reliability. The headless driver logs when its single-run guard blocks a drain (was silent) and bounds each run so a hung provider can't wedge the queue.
• Conversation rendering. Full GFM (lists/headings/blockquotes/links/tables), min-width: 0 so wide output doesn't scroll the panel, inline-code wrapping, agent-question banner contrast, and links open in a new tab with rel="noopener".

Changed

• Seed prompt carries the task inline — a compact Task grounding block (file/line/component + per-type context, via the shared task-summary) so the agent applies directly instead of reflexively calling annotask_get_task. Heavy fields (screenshot, rendered HTML, interaction history) stay behind MCP.

Verification

• Typecheck clean; full suite 1004 passed. New server tests cover the detach-grace + exit-aware finalize.
• Live smokes on the vue-vite playground with real CLIs:
  • Reload survival (HTTP): apply run + disconnect → CLI kept running → task landed review; force-kill → pending.
  • Provider routing (Playwright, all four CLIs found+logged-in): selecting copilot/codex/opencode/claude each spawned that CLI (not claude-local), no ENOENT.
  • Agent-pin persistence (Playwright): copilot + custom model saved, displayed, and survived a full reload (no wipe).

Notes

• npm publish runs locally (npm MFA/OTP), not via the release workflow.
• Follow-up (not in this PR): show "Inherit (active provider)" for unpinned built-in personas in the Agents panel; optional live-streaming reattach view on reload.

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