feat: format compact portfolio numbers

docs/journals/260722-1119-compact-portfolio-number-plan.md

@@ -0,0 +1,39 @@
+---
+date: 2026-07-22
+component: stock-and-coin-portfolios
+status: completed
+---
+
+# Compact Portfolio Number Plan
+
+## Context
+
+Full monetary values make the stock and coin Telegram portfolio position tables
+wide and difficult to scan.
+
+## What Happened
+
+The compact format work is done. Automatic `k/M/B/T` suffixes now apply to
+stock and coin position values with at most three trimmed fractional digits.
+Stock keeps Vietnamese separators; coin keeps USD separators and `$`. Only the
+position `Avg`, `Now`, `Value`, and `Unrealized P&L` fields were compacted.
+
+- [Brainstorm report](../../plans/reports/260722-1112-compact-portfolio-number-format.md)
+- [Implementation plan](../../plans/260722-1114-compact-portfolio-numbers/plan.md)
+
+## Reflection
+
+Per-value scaling still beats fixed units per column or unit labels in headers.
+It keeps the table readable without changing summaries or non-portfolio output.
+
+## Decisions
+
+- Compact only position `Avg`, `Now`, `Value`, and `Unrealized P&L` amounts.
+- Keep percentages, summaries, `N/A`, and non-portfolio replies unchanged.
+- Focused tests, full tests, `go vet`, and `golangci-lint` all passed.
+- A pre-existing extreme-finite overflow in legacy full-value formatters was
+  observed separately and left as optional follow-up, not part of this change.
+
+## Next
+
+No further action required for this change set.