feat: session modes (Talk/Cash) + live session HUD

Lyra now switches register based on what she's doing at the table instead of
being a wishy-washy companion mid-session.

Modes (lyra/modes.py):
- Talk (default companion) + Cash (live cash copilot); a mode = prompt card +
  tool allow-list. Tool gating via tools.specs(allow=).
- Two-register Cash voice: act-first one-line logging when fed facts; full warm
  companion voice for strategy / tilt / mental game.
- mode persisted per chat session (new sessions.mode column); auto-switch into
  Cash when start_session fires; UI forces cloud backend in Cash (tools only
  fire there).

Stack tracking + HUD:
- log_stack tool + poker_stack_log table; live net while sitting (stack - buy-in).
- poker.hud() bundle; /session HUD page (stack sparkline, hands, villains, notes,
  stats) polling /session/data every 5s; Talk/Cash switcher + Session nav.

Endpoints: /session, /session/data, GET/POST /sessions/{id}/mode, /modes.
tests/test_modes.py (gating, mode roundtrip, stack/HUD); 36 tests green. v0.3.0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/tools.py

@@ -104,6 +104,19 @@ def _add_buyin(args: dict, ctx: dict) -> str:
     return f"Added {args.get('amount')}. Total in this session: {total:g}."
 
 
+def _log_stack(args: dict, ctx: dict) -> str:
+    try:
+        amount = float(args.get("amount"))
+    except (TypeError, ValueError):
+        return "Give me a number for the stack."
+    try:
+        st = poker.log_stack(amount)
+    except ValueError:
+        return "No live session — start one first, then I'll track your stack."
+    net = st.get("net")
+    return f"Stack ${amount:g} logged" + (f" (net {net:+.0f})." if net is not None else ".")
+
+
 def _log_hand(args: dict, ctx: dict) -> str:
     fields = {k: args.get(k) for k in poker._HAND_FIELDS if args.get(k) not in (None, "")}
     hid = poker.log_hand(**fields)
@@ -268,6 +281,13 @@ TOOLS.update({
     "add_buyin": {"handler": _add_buyin, "spec": _f(
         "add_buyin", "Record a rebuy / additional buy-in in the live session.",
         {"amount": {**_N, "description": "Amount added"}}, ["amount"])},
+    "log_stack": {"handler": _log_stack, "spec": _f(
+        "log_stack",
+        "Record Brian's CURRENT total chip stack in the live session. Call whenever "
+        "he states his stack ('I'm at 350', 'down to 220', 'stacked off to 900'). "
+        "Tracks his stack over time and his live net while he's still sitting.",
+        {"amount": {**_N, "description": "Current total chip stack, in dollars"}},
+        ["amount"])},
     "log_hand": {"handler": _log_hand, "spec": _f(
         "log_hand",
         "Log a hand in the live session. All fields optional — capture whatever Brian gives you, even terse.",
@@ -353,9 +373,16 @@ TOOLS.update({
 })
 
 
-def specs() -> list[dict]:
-    """OpenAI-format tool definitions to offer the model."""
-    return [t["spec"] for t in TOOLS.values()]
+def specs(allow=None) -> list[dict]:
+    """OpenAI-format tool definitions to offer the model.
+
+    `allow` (an iterable of tool names, e.g. a mode's allow-list) restricts the
+    set; None means every tool. Unknown names in `allow` are ignored.
+    """
+    if allow is None:
+        return [t["spec"] for t in TOOLS.values()]
+    allow = set(allow)
+    return [t["spec"] for name, t in TOOLS.items() if name in allow]
 
 
 def dispatch(name: str, arguments, ctx: dict | None = None) -> str: