Add Schwab email parser (port from finance/)

Schwab's workplace-RSU confirmation emails have 5 data td elements
with class='dark-background-body' align='right': date, direction, qty,
ticker, price-with-currency-sign. One email → one Activity.

- parse_schwab_email(raw_html) -> list[Activity] (1-item or empty)
- Empty on any parse failure (IMAP batch shouldn't crash on one bad mail)
- Deterministic external_id ('schwab📅ticker:type:qty') — stable
  across re-pulls so dedup works
- Hardcoded to account 'schwab-workplace' / AccountType.GIA / USD
- 6 unit tests: SELL + BUY happy path, malformed, missing cells,
  external-id stability, commas in price

Dropped from the original finance port:
- msg_timestamp-based external id (non-deterministic — would re-import
  on every IMAP walk). Replaced with a hash-stable key.
- Currency.from_sign() currency hack. Schwab US is USD-only; we'll add
  FX when that changes.

poetry run pytest -q   →  109 passed, 1 skipped
poetry run mypy        →  clean (added types-python-dateutil)
poetry run ruff check  →  clean

broker_sync/providers/parsers/schwab.py

@@ -0,0 +1,75 @@
+"""Schwab workplace-RSU email parser.
+
+Schwab sends HTML transaction-confirmation emails with the core fields in
+five `<td class="dark-background-body" align="right">` elements:
+1. Trade date (human format — e.g. "Jan 23, 2025")
+2. Direction word ("Sold" for SELL; anything else is BUY)
+3. Quantity (share count, float)
+4. Ticker
+5. Price ("$123.45" — currency-sign-prefixed)
+
+One email → one Activity. On any parse failure we return an empty list
+(same as the original finance/ behaviour — an unparseable email shouldn't
+crash the whole IMAP batch).
+
+Ported from finance/position/provider/schwab/message_parser.py (39 lines).
+Dropped: per-row timestamp id suffix (we use ISO date + ticker + qty which
+is stable across re-pulls), currency-from-sign hackery (US Schwab is USD-
+only in practice — if that ever changes we'll add FX on parse).
+"""
+from __future__ import annotations
+
+from decimal import Decimal, InvalidOperation
+
+from bs4 import BeautifulSoup
+from dateutil import parser as dateparser
+
+from broker_sync.models import AccountType, Activity, ActivityType
+
+_ACCOUNT_ID = "schwab-workplace"
+_DEFAULT_CURRENCY = "USD"
+
+
+def parse_schwab_email(raw_html: str) -> list[Activity]:
+    """Return a single-item list of Activity on success, empty on failure."""
+    try:
+        soup = BeautifulSoup(raw_html, "html.parser")
+        cells = [
+            td.get_text(strip=True) for td in soup.find_all("td", {
+                "class": "dark-background-body",
+                "align": "right"
+            })
+        ]
+        if len(cells) < 5:
+            return []
+
+        date_txt, direction_txt, qty_txt, ticker, price_txt = cells[:5]
+        trade_date = dateparser.parse(date_txt)
+        direction = (ActivityType.SELL
+                     if direction_txt.strip().lower() == "sold" else ActivityType.BUY)
+        quantity = Decimal(qty_txt.replace(",", "").strip())
+        # Price like "$123.45" — strip the currency sign and parse the numeric tail.
+        # Handle "£", "€", "USD", etc. by taking the last numeric span.
+        price_clean = price_txt
+        for sign in ("$", "£", "€", "USD", "GBP", "EUR"):
+            price_clean = price_clean.replace(sign, "")
+        unit_price = Decimal(price_clean.replace(",", "").strip())
+
+        external_id = (f"schwab:{trade_date.date().isoformat()}:{ticker}:"
+                       f"{direction.value}:{quantity}")
+        return [
+            Activity(
+                external_id=external_id,
+                account_id=_ACCOUNT_ID,
+                account_type=AccountType.GIA,
+                date=trade_date,
+                activity_type=direction,
+                symbol=ticker.strip(),
+                quantity=quantity,
+                unit_price=unit_price,
+                currency=_DEFAULT_CURRENCY,
+                notes=f"schwab-email:{direction_txt}",
+            )
+        ]
+    except (ValueError, InvalidOperation, IndexError, AttributeError):
+        return []