feat: expense tracker Python parity (Wave 10)

New `expenses_handlers.py`:
- parse_expense(phrase) -> (amount, category) | None  — pure fn, fully
  unit-tested. Handles "потратил 500 на еду", comma decimals "12,50",
  EN "spent 12.5 on coffee", default category "разное".
- do_expenses_log: append entry to expenses.json (atomic write-then-rename).
- do_expenses_today: sum today's entries (local-day boundary).
- do_expenses_week: rolling 7-day total + count.
- do_expenses_breakdown: per-category, top-5 + tail collapse.

extensions.py / main.py / commands.yaml: 4 new dispatch entries.
.gitignore: + expenses.json.

tests/test_expenses_handlers.py: 8 unit tests covering parse, log,
today/week math, breakdown ordering + tail collapse.

Tests: 96 → 104 (+8). Total Python coverage now mirrors Rust pack
behaviour for personal finance.

extensions.py

@@ -32,6 +32,7 @@ import personality_handlers
 import time_tracker_handlers
 import outlook_handlers
 import wave68_handlers
+import expenses_handlers
 
 _speak_fn = print
 _set_clipboard_fn = None
@@ -49,6 +50,7 @@ def set_speak(fn):
     time_tracker_handlers.set_speak(fn)
     outlook_handlers.set_speak(fn)
     wave68_handlers.set_speak(fn)
+    expenses_handlers.set_speak(fn)
 
 
 def set_clipboard_fn(fn):
@@ -1166,3 +1168,11 @@ def do_trivia(a, v): wave68_handlers.do_trivia(a, v)
 def do_good_night(a, v): wave68_handlers.do_good_night(a, v)
 def do_good_morning(a, v): wave68_handlers.do_good_morning(a, v)
 def do_coffee_break(a, v): wave68_handlers.do_coffee_break(a, v)
+
+
+# ── Expenses proxies (to expenses_handlers) ────────────────────────────────
+
+def do_expenses_log(a, v): expenses_handlers.do_expenses_log(a, v)
+def do_expenses_today(a, v): expenses_handlers.do_expenses_today(a, v)
+def do_expenses_week(a, v): expenses_handlers.do_expenses_week(a, v)
+def do_expenses_breakdown(a, v): expenses_handlers.do_expenses_breakdown(a, v)