feat: Wave 10 — expense tracker pack (voice-driven)

resources/commands/expenses/ (4 commands):
- expenses.log     "потратил 500 на еду"     → append entry
- expenses.today   "сколько потратил сегодня" → today's total
- expenses.week    "сколько на неделе"       → 7-day rolling total
- expenses.breakdown "куда ушли деньги"      → top-5 categories

Storage: `jarvis.state` (auto-namespaced per-pack JSON). Wire format is
compact "ts1,amount1,cat1|ts2,amount2,cat2" so we don't need a JSON parser
inside Lua.

Phrase parsing:
- Trigger stripped via jarvis.text.strip_trigger.
- First number captured; "12,50" comma decimals accepted.
- Category extracted from "на <слово>" (RU) or "for/on <word>" (EN);
  defaults to "разное" / "misc".

Time math:
- Day boundary: local-calendar midnight via os.time({year,month,day,...}).
- Week boundary: rolling 7×86400 seconds.

Pack count: 98 → 99 functional.

resources/commands/expenses/log.lua

@@ -0,0 +1,74 @@
+-- Voice "потратил 500 на еду" → append {amount, category, timestamp} to the
+-- pack's state JSON.
+--
+-- Parsing the phrase:
+--   1. Strip the trigger ("потратил" / "spent" / ...)
+--   2. First number = amount
+--   3. After the number: optional "на <слово>" → category (RU) or "for <word>"
+--      / "on <word>" (EN). Otherwise category defaults to "разное" / "misc".
+
+local lang = jarvis.context.language
+local raw = (jarvis.context.phrase or ""):lower()
+
+local triggers = {
+    "потратил", "записать трату", "запиши трату", "купил за", "заплатил за",
+    "spent", "log expense", "paid for", "bought",
+}
+local rest = jarvis.text.strip_trigger(raw, triggers) or raw
+rest = rest:gsub("^%s+", ""):gsub("%s+$", "")
+
+-- Pull the first integer-like token. Allows comma decimals ("12,50" → 12.5).
+local amount_str, after = rest:match("(%-?[%d]+[%.,]?[%d]*)%s*(.*)")
+if not amount_str then
+    return jarvis.cmd.not_found(lang == "ru"
+        and "Не понял сумму, сэр."
+        or  "I didn't catch the amount, sir.")
+end
+amount_str = amount_str:gsub(",", ".")
+local amount = tonumber(amount_str)
+if not amount or amount <= 0 then
+    return jarvis.cmd.not_found(lang == "ru"
+        and "Сумма не похожа на число."
+        or  "That doesn't look like an amount.")
+end
+
+local category = "разное"
+local cat_match = (after or ""):match("на%s+(%S+)") or (after or ""):match("for%s+(%S+)")
+                or (after or ""):match("on%s+(%S+)")
+if cat_match and cat_match ~= "" then
+    category = cat_match
+end
+
+-- Load existing log, append, save.
+local raw_state = jarvis.state.get("entries") or ""
+local entries = {}
+if raw_state ~= "" then
+    -- Encoded as "ts1,amount1,cat1|ts2,amount2,cat2|..."
+    for chunk in raw_state:gmatch("([^|]+)") do
+        local ts, am, ca = chunk:match("^(%d+),([%-%d%.]+),(.+)$")
+        if ts and am and ca then
+            table.insert(entries, { ts = tonumber(ts), am = tonumber(am), ca = ca })
+        end
+    end
+end
+
+local now = jarvis.context.time
+-- chrono::Local timestamp is exposed via {year, month, day, hour, minute, second}
+-- but not as a unix epoch. Approximate via os.time({...}) — sandbox standard
+-- gives us os.time/date.
+local ts = os.time({
+    year = now.year, month = now.month, day = now.day,
+    hour = now.hour, min = now.minute, sec = now.second or 0,
+})
+table.insert(entries, { ts = ts, am = amount, ca = category })
+
+local out = {}
+for _, e in ipairs(entries) do
+    table.insert(out, string.format("%d,%s,%s", e.ts, tostring(e.am), e.ca))
+end
+jarvis.state.set("entries", table.concat(out, "|"))
+
+return jarvis.cmd.ok(string.format(lang == "ru"
+    and "Записал: %s на %s."
+    or  "Logged: %s on %s.",
+    amount_str, category))