fix(tasks): restore session context on Resume/Launch from kanban board

[kadeross]

Problem

Three compounding bugs caused agents to get zero real conversation history when clicking Resume or Launch from a kanban task card.

Root Causes

1. Wrong context source
Prior session history was read from .runtime/local-sessions.json (the workspace's in-memory local store), which only ever holds the initial briefing message. The actual conversation lives in the Hermes gateway SQLite DB on port 9119.

2. Wrong session ID on the task
On launch, the workspace generates a placeholder ID (task-<uuid>-<uuid>) and writes it to task.session_id. The real Hermes gateway session ID — created when the user sends the first message — was never written back. So even querying the right source failed because the ID was wrong.

3. Tail too short / truncated
Only the last 8 messages at 500 chars each — not enough to reconstruct meaningful state for most tasks.

Fix

src/routes/api/hermes-tasks.$taskId.ts — launch action now:

• Queries the dashboard API (port 9119) for real message history first
• Falls back to local store if dashboard is unavailable
• Tail expanded to 20 messages × 800 chars

src/screens/tasks/tasks-screen.tsx — on successful launch:

• Stores a hermes-task-wsession:<wsSessionId> → taskId mapping in localStorage so the chat route can back-link the real session

src/routes/chat/$sessionKey.tsx — in handleSessionResolved:

• Reads the localStorage mapping when the gateway resolves the real session ID
• Fires a PATCH to update task.session_id with the real gateway session ID
• Future Resume/Launch calls now query the correct session in the dashboard

src/server/claude-dashboard-api.ts + src/server/claude-api.ts:

• Add sendChat export that routes through port 9119 (dashboard) when available, fixing the Launch routing bug (was hitting port 8642 / zero-fork mode which returns 404)

src/routes/api/hermes-tasks.ts + hermes-tasks.$taskId.ts + hermes-tasks-assignees.ts:

• Tasks board API routes (CRUD + assignee listing) that back the kanban UI

Testing

1. Create a task on the board, click Launch — work with the agent for several turns
2. Close the chat, reopen the task dialog
3. Click Launch New Session — the new briefing should include the last 20 messages of prior conversation
4. The Resume Session link should also navigate to the real gateway session (not the placeholder)

[outsourc-e]

Closing as superseded by #432. The validated fix was folded into the consolidated batch branch fix/issue-sweep-batch-20260514 for one review/merge path.