feat(data ingest): data-first flow inversion + family-scoped task picker (#180b)

[LukasWodka]

Stacked on #197 / #180a — merge after those. Base is feat/180a-task-split-name-renames; this is the second half of cli#180 (the data-first flow inversion of RFC-0002). The --task/--name renames shipped in #180a; --intent stayed as --intent.

Closes#180

What changed

Inverts the guided data ingest flow to data-first and reworks task selection so the user never faces the flat 15-task wall.

1. Prompt reorder (§12.1): intent → name → path → task → task-specific → review. Name is prompted with an example in the hint, not auto-filled.
2. Family sniff + echo (§5.1): after the path, the family is detected from the layout and echoed (Found a CSV table — this is tabular data.). The sniff is a hint, not a lock — ambiguous layout asks plainly, an explicit --task skips the sniff, non-interactive never sniffs. SniffFamily mirrors the Discover* layout markers and validates nothing (Principle 6 — no forked validation).
3. Family-scoped task picker (§7): only that family's tasks, rendered Display — one-liner · task_id, split into Available now vs greyed Not yet in the CLI (with reason). Wires the registry Label (was dead code) + the locked glosses (time_to_event_prediction → Survival analysis, masked_language_modeling → fill-mask, seq2seq → translation / summarization) + a per-task blurb.
4. Label question (§8): interactive now selects the label column from the real CSV header (exact match kills the data-ingestors#340 case-mismatch silent-null-label class), worded per task (class vs value-to-predict), skipped for self-supervised text; free-text fallback if the header can't be read. --number-of-keypoints / --time-column unchanged.
5. Promptable overwrite (folded): a pre-existing table is a y/N prompt interactively (yes → replace, no → clean exit 0), still a hard exit 6 non-interactively; a reused --idempotency-key falls through to exit 6 (preserves the data-loss guard).
6. Copy polish (folded from data ingest: plain-language copy + reduce ceremony (RFC-0002 phase 1) #179): data/ingest help says "workspace"/"ingest", not "client"/"stage". Aliases unchanged.

Guardrails held

Exit-code / classify / reclaim matrix unchanged except the deliberate promptable-overwrite. No NULL-label path. --output-json keys unchanged. All output via internal/ui Printer methods.

Tests

go build ./... && go test ./... && gofmt -l . (empty) && go vet ./... — all green. New coverage: prompt order, sniff echo + hint-not-lock + explicit-task-skips-sniff, family-scoped picker (excludes other families, shows pending, DS names + glosses), label-select-from-headers + per-task wording + self-supervised skip + free-text fallback, promptable overwrite (interactive y/n + non-interactive exit-6 + idempotency-key fall-through), and push-level SniffFamily / PreviewLabelHeaders / DisplayName glosses.

🤖 Generated with Claude Code

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Note

Medium Risk
Changes core ingest UX and overwrite semantics for interactive runs; preview/sniff logic must stay aligned with Discover* to avoid misleading users before the real walk fails.

Overview
Implements RFC-0002 data-first guided data ingest: prompts run intent → name → path → task (then task-specific fields and review), with workspace/ingest copy updates in help text.

After the path, SniffFamily previews layout (read-only, aligned with Discover*) and echoes confident cases; ambiguous layouts ask the family plainly. --task skips sniff and the flat task list. The picker uses CategoriesByFamily with display names, glosses, blurbs, and Available now vs Not yet in the CLI.

Interactive label columns come from a SELECT on real CSV headers (PreviewLabelHeaders), with regression vs classification wording and no label prompt for self-supervised text (SelfSupervised on the registry).

When a destination table already exists without --overwrite, interactive TTY users get a replace y/N (no → exit 0); non-interactive / --output-json still exit 6. Reused --idempotency-key never gets the prompt (data-loss guard).

findSingleCSV is shared so tabular sniff, header preview, and DiscoverTabular stay on the same single-CSV rule.

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