Pivot to text-first column-stack workspace + merge-with-review across AI artifacts

Workspace
- Pivot from "set of open panes" to a Finder-style miller column stack:
  TopBar / LeftSidebar / [section → entity → entity ...] / pinned text editor.
  openPanesStore is now an ordered Column[] with pushFrom / closeFrom /
  setStack; only one top-level section is rooted at a time.
- New entity column panes: Term, Block, Association, Constraint,
  Requirement, Finding. Click-through navigation truncates deeper
  columns automatically.
- LeftSidebar surfaces a pending-count chip per section (single-glance
  navigation cue) and spins its analyze ↻ via SVG Spinner whenever the
  LLM is working — including server-initiated runs caught by the runs
  poll, not just user-triggered ones.

Analyze pipeline + persistence
- Unified `concepts` pass (taxonomy + glossary in one LLM call) replaces
  the two-pass setup. Server still accepts ?section=taxonomy|glossary
  and normalizes them for back-compat.
- model / requirements / detection (assumptions, risks, inconsistencies)
  + cross-layer validation rules (X1–X4: stale term link, unlinked
  formalism, undefined linked term, prose-only term).
- Persistence: NarrativeDocument, ModelSnapshot, ChangelogEntry,
  TaxonomyTerm, RequirementEntry, Finding, AnalysisRun. Re-runs MERGE
  instead of replace: gentle update on existing items, suggested on new,
  deprecated on missing — same idiom for every artifact kind. User pins
  preserve "kept" decisions across re-analyses.
- Migrations: pivot_text_first, add_requirement_linked_term,
  term_review_state, review_state_for_reqs_and_findings,
  add_term_definition_pinned.

Concept ↔ ontology integration
- linkedTermId on Block / Association / Constraint / Requirement.
  PromoteToolbar lets the user formalize a concept inline: + Block /
  + Association / + Constraint / + Requirement, all routed through
  applyOps so undo/redo and SSE work for free.
- decideElement op for in-canvas keep/discard on review-pending model
  elements.

User-authored definitions
- TermColumn definition is click-to-edit. Save (Cmd-Enter / blur),
  Cancel (Esc), Reset to AI suggestion when pinned.
- definitionPinned flag on TaxonomyTerm: future Analyze runs leave the
  user's text alone. setTermDefinition repo function + POST
  /api/projects/[id]/terms/[termId]/definition endpoint.
- mergeTaxonomySuggestion + applyGlossaryDefinitions both pin-aware.

UX/UI
- StatusChip: single component for all state idioms (suggested,
  deprecated, accepted, dismissed, resolved, severity, validation code,
  confidence, warn). Replaces 5+ ad-hoc badge classes.
- PaneControls (PaneViewTabs + PaneFilterChip): separates view-mode
  toggles from filter chips so toggling Pending no longer flips you off
  the current view.
- PaneEmpty: unified empty-state with title + hint + action.
- PaneDrawer: collapsible groups for Pending / Discarded review; cards
  group as Kept (top) → Pending (bottom drawer) → Discarded (Findings
  only, hidden when empty). Restore action recovers dismissed/resolved
  findings.
- ConceptCard unifies Tree and A–Z views in Concepts; only Tree parents
  carry the chevron (no empty placeholder offset).
- Type + spacing tokens (--text-xs..xl, --space-1..6, --lh-tight/ui/
  prose, --radius-*) replace every ad-hoc value.
- Buttons standardized to body sans 500 (was a mishmash of mono / display).
- Card shells unified across Concepts / Requirements / Findings.

Cleanup
- Removed: LeftRail, FindingsPanel, IssuesPanel, SocratesDock,
  ProposalCard, SlashMenu, SlashExtension, slashSuggestion,
  CanvasHeader, TaxonomyPane, GlossaryPane, TermDetail (popover; now
  TermColumn).
- Section ids in openPanesStore: dropped taxonomy/glossary, added
  concepts. localStorage migration runs on hydrate.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/components/editor/Spinner.tsx

@@ -0,0 +1,74 @@
+// Spinner — a small, polished SVG ring used everywhere the UI needs to
+// signal "working." Two stacked circles: a faint full ring (track) and a
+// shorter accent arc on top, with the arc rotating around the center.
+// The dasharray + animation give a smooth motion that doesn't depend on
+// CSS-only border tricks (which look chunky at small sizes).
+
+"use client";
+
+interface SpinnerProps {
+  /** Pixel size; defaults to 14 (matches sidebar button glyph metrics). */
+  size?: number;
+  /** Accent stroke color; defaults to `currentColor` so the spinner picks
+   *  up the surrounding text color. */
+  color?: string;
+  /** Track stroke color; defaults to a faint border tone. */
+  trackColor?: string;
+  /** Stroke width in SVG units (viewBox 24×24). 2.5 reads cleanly at 14px. */
+  strokeWidth?: number;
+  className?: string;
+  title?: string;
+}
+
+export function Spinner({
+  size = 14,
+  color = "currentColor",
+  trackColor = "rgba(0,0,0,0.14)",
+  strokeWidth = 2.5,
+  className,
+  title,
+}: SpinnerProps) {
+  return (
+    <svg
+      className={`spinner ${className ?? ""}`}
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      role={title ? "img" : "presentation"}
+      aria-label={title}
+      aria-hidden={title ? undefined : true}
+    >
+      {/* Track */}
+      <circle
+        cx="12"
+        cy="12"
+        r="9"
+        fill="none"
+        stroke={trackColor}
+        strokeWidth={strokeWidth}
+      />
+      {/* Animated arc — strokeDasharray ~= 25% of the circumference (2π·9 ≈ 56.5);
+       * we use 14 56.5-14 = 14 / 42.5 to draw a 14-unit arc. */}
+      <circle
+        cx="12"
+        cy="12"
+        r="9"
+        fill="none"
+        stroke={color}
+        strokeWidth={strokeWidth}
+        strokeLinecap="round"
+        strokeDasharray="14 42.5"
+        transform="rotate(-90 12 12)"
+      >
+        <animateTransform
+          attributeName="transform"
+          type="rotate"
+          from="-90 12 12"
+          to="270 12 12"
+          dur="0.85s"
+          repeatCount="indefinite"
+        />
+      </circle>
+    </svg>
+  );
+}