docs: add value proposition

docs/workshop/valueproposition.md

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+# Value Proposition — travelledger
+
+## One-line
+**travelledger is the calm, single place for your whole trip — itinerary, expenses,
+booking QR codes, and cancellation deadlines — with stats and AI help when you want them.**
+
+## Customer problem (the "why now")
+Travel data is scattered: confirmation emails in Gmail, QR codes in photos, expenses
+in notes, cancellation dates in nobody's memory. Existing tools are either generic
+notes (Notion/Airtable — you build it yourself) or booking silos (OTAs — they want to
+sell, not organize). After a trip, nobody can answer "how much did we actually spend,
+and on what?"
+
+## Value proposition canvas (converged)
+
+### Customer jobs
+- Organize the full itinerary (flights, hotels, trains) in one view.
+- Capture and categorize expenses as they happen.
+- Never miss a cancellation/refund window.
+- Keep booking QR codes (boarding pass, hotel check-in, rail) accessible offline.
+- Get post-trip stats across currencies.
+
+### Pains we remove
+- Lost confirmations and degraded receipt photos.
+- Sunday-night expense-report drudgery.
+- Missed cancellation deadlines → wasted money.
+- "How much did this trip cost?" with no answer.
+- App-switching between diary, wallet, spreadsheet.
+
+### Gains we create
+- Control and calm during the trip.
+- Fast, auditable reimbursements.
+- A real travel memory + data archive.
+- Proactive "Trip Guardian" alerts before deadlines.
+- (Later) one-tap booking of hotels/tours with affiliate convenience.
+
+### Pain relievers
+- Attach QR/PDF per segment; offline cache; encrypted at rest.
+- Auto-categorize expenses via AI (opt-in); export to Excel/QuickBooks.
+- Cancellation-rule engine with push reminders.
+- Post-trip dashboards (category %, per-day, per-currency).
+
+### Gain creators
+- Beautiful shared trip pages (viral loop).
+- AI trip summaries ("you spent 40% on food across 5 cities").
+- (Later) in-app booking with embedded insurance.
+
+## Differentiators / moat
+1. **Neutral + trusted** — not an OTA; we organize, we don't lock you in to buy.
+2. **Trip Guardian (AI)** — proactive cancellation + categorization is the emotional hook
+   and the defensible layer.
+3. **One codebase → web + iOS + Android** (Next.js + Capacitor) → fast, consistent iteration.
+
+## Target persona priority (validated order)
+1. **Corporate Carla** — clear pain, reimbursement budget, workflow stickiness.
+2. **Digital Nomad Dana** — tax/visa pain, high willingness to pay, data stickiness.
+3. **Family Festival Fred** — shared-page viral loop, seasonal burst willingness.
+4. **Travel Agent Tina** — B2B wedge, referrals (later).
+
+## Positioning statement
+*For frequent travelers and trip organizers who juggle scattered confirmations and
+expenses, travelledger is a mobile-first travel ledger that unifies itinerary, spend,
+and booking QR codes — and guards your cancellation deadlines — so you finish every
+trip informed, reimbursed, and unstressed. Unlike OTAs, it's neutral; unlike note
+apps, it's purpose-built.*