docs: create roadmap (5 phases) and research

Phases:
1. Foundation: tenant isolation, auth, Docker, RBAC
2. Subscriber & Billing Core: subscribers, invoicing, payments, accounting ledger
3. Operational Modules: collectors, ticketing, job orders, technicians
4. Inventory, Expenses & Reports: event-ledger inventory, expenses, financial statements
5. Visibility & Client Portal: dashboard, client self-service, integration & e2e tests

All 66 v1 requirements mapped to phases.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/STATE.md

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+# Project State
+
+## Project Reference
+
+See: .planning/PROJECT.md (updated 2026-03-04)
+
+**Core value:** ISP owners can see exactly where their money is — who owes what, what's been collected, what's been spent, and what the business actually looks like financially — in real time.
+**Current focus:** Phase 1 - Foundation
+
+## Current Position
+
+Phase: 1 of 5 (Foundation)
+Plan: 0 of 5 in current phase
+Status: Ready to plan
+Last activity: 2026-03-04 — Roadmap created, STATE.md initialized
+
+Progress: [░░░░░░░░░░] 0%
+
+## Performance Metrics
+
+**Velocity:**
+- Total plans completed: 0
+- Average duration: -
+- Total execution time: 0 hours
+
+**By Phase:**
+
+| Phase | Plans | Total | Avg/Plan |
+|-------|-------|-------|----------|
+| - | - | - | - |
+
+**Recent Trend:**
+- Last 5 plans: none yet
+- Trend: -
+
+*Updated after each plan completion*
+
+## Accumulated Context
+
+### Decisions
+
+Decisions are logged in PROJECT.md Key Decisions table.
+Recent decisions affecting current work:
+
+- [Roadmap]: Accounting COA and JournalEntryService built in Phase 2 before first invoice — cannot be retrofitted
+- [Roadmap]: Inventory modeled as event-ledger (immutable movements) from Phase 4 — mutable quantity columns explicitly rejected
+- [Roadmap]: Collector balances derived from transaction log, never stored as mutable fields
+- [Roadmap]: PORT-05 (online payment) scaffolded in Phase 5 but payment gateway integration deferred to v2 per project out-of-scope decision
+
+### Pending Todos
+
+None yet.
+
+### Blockers/Concerns
+
+- [Phase 1 research flag]: MikroTik RouterOS Node.js client library maintenance status is LOW confidence — verify `node-routeros` vs `mikronode` before implementing router integration (MikroTik integration is v2, but adapter interface should be planned)
+- [Phase 3 research flag]: Semaphore SMS API pricing/stability for 2026 is MEDIUM confidence — verify before any SMS work (SMS is v2, but abstraction layer design is relevant)
+
+## Session Continuity
+
+Last session: 2026-03-04
+Stopped at: Roadmap created. ROADMAP.md, STATE.md written. REQUIREMENTS.md traceability updated. Ready to plan Phase 1.
+Resume file: None