Feat(mcp): list_tasks says which status column each task is in, as zn mcp does

[adibhanna]

For #941, and the desktop half of ZenNotes/tui#10: an assistant reading tasks through the desktop's MCP server now sees which status column each task is in, as it does through zn mcp.

What changes

• list_tasks returns status on every task note (its frontmatter status:, open when it has none) and on every checkbox line that has one (its first @status:, or the status: of its note's frontmatter), lower-cased. A line without one has no status key.
• Content and ids do not change: this grammar keeps @status: in content, as it keeps every field.
• inlineTaskField, the app's own field reader, is exported from packages/shared-domain/src/tasks.ts and imported by vault-ops.ts instead of being copied again.
• The tool description names the field, and the status argument says it filters by state (open, done, waiting), not by that column, in the same words as zn mcp.
• The legacy TypeScript CLI shares this scan, so its task list --json gains status too, matching the Go zn.

Verification

• npx vitest run src/mcp/ (63 tests, 1 new) and shared-domain (1,994) pass; desktop and shared-domain typecheck clean.
• The new test checks every line's status against shared-domain's parseTasksFromBody, so the MCP server and the app cannot drift apart.
• Built out/main/mcp.js, ran it with ELECTRON_RUN_AS_NODE=1 on a scratch vault and called list_tasks over stdio: the same ids, content and statuses as zn mcp from Feat(tasks): zn task watch prints each task status change as it happens tui#10, and tools/list shows the new descriptions.

How to test locally

cd apps/desktop && npx electron-vite build
mkdir -p /tmp/mcp-status/vault/inbox /tmp/mcp-status/cfg
printf -- '---\ntags: [task]\nstatus: backlog\n---\nBuild it.\n' > /tmp/mcp-status/vault/inbox/Parser.md
printf -- '- [ ] Write docs @status:Review\n- [ ] Plain task\n' > /tmp/mcp-status/vault/inbox/Sprint.md
printf '{"workspaceMode":"local","vaultRoot":"/tmp/mcp-status/vault"}\n' > /tmp/mcp-status/cfg/zennotes.config.json
ZENNOTES_CONFIG_DIR=/tmp/mcp-status/cfg ELECTRON_RUN_AS_NODE=1 npx electron out/main/mcp.js <<'EOF' 2>/dev/null | tail -1 | jq -r '.result.content[0].text' | jq -c '.[] | {content, status}'
{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"check","version":"1"}}}
{"jsonrpc":"2.0","method":"notifications/initialized"}
{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"list_tasks","arguments":{"status":"all"}}}
EOF

Before this change no task has a status. After it: Parser is backlog, Write docs @status:Review is review, and Plain task has none. zn mcp from ZenNotes/tui#10 gives the same answer for the same vault.