feat(profile-distribution): paired histogram cells for inline profile (DRC-3390 PR 3)

[danyelf]

Summary

PR 3 of the DRC-3390 paired-histograms GA productionization (4-PR stack). Adds the frontend cells, hook, schema-row integration, and unsupported-adapter banner that consume the per-column payloads PR 2 produces.

Stacks on #1389. Mocks PR 2 payload until #1389 merges. Rebase onto main after PR 2 merges.

Adds

• PairedHistogramContinuous — quantile-bin, constant-area paired bar chart. Heights = density, widths = bin span, so bar area reads as the proportion of rows in that bin. Replaces the prototype's uniform-bin renderer (closed PR feat(schema): bubble-up paired histograms + inline profile in schema view #1380).
• PairedHistogramDiscrete — top-K paired chart with gap-on-absent semantics. When a value is missing on one side, that bar isn't drawn, leaving a visible empty half-slot that reads as "absent here."
• useInlineProfileDistribution — TanStack-Query-backed hook that fires a single PROFILE_DISTRIBUTION run per model, parses the discriminated-union payload, and returns {distributions, loading, error, isUnsupported}. Emits Amplitude analytics events at request and result (DRC-3390 says PostHog, codebase uses Amplitude — same trail).
• InlineProfileDistributionCell — Compact-mode wrapper that picks between loading / error / empty (per-column failure) / continuous / discrete renders in a fixed-size slot so adjacent rows don't reflow. Grid mode is intentionally absent at GA.
• ProfileDistributionUnsupportedBanner — once-per-task MUI Alert for the {status: 'unsupported', reason} envelope (Postgres / MySQL / SQLite / SQL Server pre-2022).

Payload contract (frozen — PR 2 produces exactly this)

• Continuous: {kind:'histogram', bin_edges:[12], base_density:[11], current_density:[11], base_total, current_total}
• Categorical: {kind:'topk', values, base_counts, current_counts, base_total, current_total, trimmed}
• Per-column failure: {kind:null}
• Unsupported envelope: {status:'unsupported', reason:...}

Refines ProfileDistributionResult in api/types/run.ts from PR 1's stub Record<string, unknown> to the full discriminated union.

Out of scope (per DRC-3390 locked decisions)

• Grid mode (Compact only at GA)
• Lineage pre-warm / hover-grazing (PR 4)
• SQLMesh adapter coverage

Also fixes baseline regressions PR 1 introduced

• chore(run-registry): PR 1 narrowed findByRunType to RegisteredRunType but left js/src/components/run/__tests__/registry.test.ts arrays typed as RunType[] — tsc flagged 3 sites. Re-typed to RegisteredRunType[].
• test(action-adapter): PR 1 added an isRegisteredRunType guard inside RecceActionAdapter but the test mock didn't stub it, breaking 9 tests with timeout failures. Added the guard to the mock.

Both committed separately so they can be reviewed (or cherry-picked back to PR 1) in isolation.

Test plan

• pnpm run --filter @datarecce/ui type:check clean (remaining errors are pre-existing CSS-module + lineage-hooks baseline noted in the project memory).
• pnpm run --filter @datarecce/storybook build succeeds.
• 57 new unit tests pass (PairedHistogramContinuous, PairedHistogramDiscrete, InlineProfileDistributionCell, ProfileDistributionUnsupportedBanner, useInlineProfileDistribution).
• Pre-push hook clean — 1933 tests pass, no leftover failures.
• 20 storybook stories rendered visually on http://localhost:6011; screenshots verified for the mixed-state Compact view, gap-on-absent, trimmed marker, loading spinner, error chrome, unsupported banner (light + dark).
• Manual smoke against the real schema view once PR 2 lands — wire useInlineProfileDistribution into the actual SchemaView Compact row and confirm cells render against a real PROFILE_DISTRIBUTION run result.

🤖 Generated with Claude Code

[danyelf]

Closing as part of restructure (Ultraplan-approved). New 4-stage vertical-slice plan replaces the original 4-PR breakdown.

This PR's content splits across:

• Stage A (Storybook-only): the three leaf cells (PairedHistogramContinuous, PairedHistogramDiscrete, ProfileDistributionUnsupportedBanner) + their unit tests + the two dedicated .stories.tsx files + fixtures.ts + SchemaRowMock.tsx. Cells refactored to use local types so Stage A has zero dependency on the API contract.
• Stage C (UI wiring): InlineProfileDistributionCell container + its 9 stories, useInlineProfileDistribution hook, api/profileDistribution.ts (submit helper + type guards), cacheKeys update, trackProfileDistribution Amplitude event, and the SchemaView Compact integration.

Branch feature/drc-3390-pr3-frontend-cells retained as a code-stash source.