F18: In-app help — user guide + glossary in the SPA #71

Part of Phase 1.1 (epic #14). Owner request (2026-07-17): the system needs usage documentation and the key concepts/glossary available inside the SPA, not just in the repo — and it must stay current with every backend/frontend change (companion rule added to AGENTS.md).

Scope

• Help route + nav entry in the SPA (/help), fully client-side content (no backend).
• User guide sections, one per screen, written for a farm operator (not a developer):
  • The daily loop: record entry → submit → lots → stock → order → confirm (spec §7 one-liner as the anchor).
  • Daily entry (draft vs submitted, copy-from-yesterday when it lands, blank vs zero).
  • Flocks (lifecycle Active/Depleted/Archived, reactivate as the undo, bird ledger, cull vs adjustment).
  • Grades (saleable flag, deactivation semantics).
  • Stock (available vs restricted).
  • Inventory (items/categories, unit lock, purchases → lots, feed usage, corrections via adjustments/discards).
  • Customers & Sales (draft orders, confirm = FIFO allocation, void = undo with stock return, cancel vs void).
  • History (filters, entry states).
• "Fixing mistakes" section — the corrections map in one place: reactivate flock, void order, inventory adjustment, and what's currently not undoable (submitted entries until F17: Edit submitted daily entries — lock job + manager adjust with lot/movement reconciliation #69).
• Glossary — farmer-facing rendition of specs/product/GLOSSARY.md (repo glossary stays the canonical spec-language version; the in-app one favors plain words). Cross-linked from screen sections.
• Searchable/anchored (simple heading anchors fine; no search infra needed).
• Responsive per F9: Responsive/mobile pass — usable on phones and tablets #49 patterns.

Maintenance rule (lands with this slice, applies forever)

AGENTS.md: every slice that adds/changes user-visible behavior updates the Help page + in-app glossary in the same PR — reviewers treat missing help updates like missing tests.

Out of scope

• i18n of help content (i18n infrastructure (API half): validation error codes + users.language + GET/PATCH /me #45 externalizes strings later; write it as ordinary TSX/markdown now, flagged for extraction).
• Backend-served docs/CMS.

Acceptance

• Every current screen has a help section reachable in ≤2 clicks; glossary terms match GLOSSARY.md meanings; the corrections map covers reactivate/void/adjust accurately.