feat: add persistent CLI status bar and usage details (#1522)

Salvaged from PR #1104 by kshitijk4poor. Closes #683.

Adds a persistent status bar to the CLI showing model name, context
window usage with visual bar, estimated cost, and session duration.
Responsive layout degrades gracefully for narrow terminals.

Changes:
- agent/usage_pricing.py: shared pricing table, cost estimation with
  Decimal arithmetic, duration/token formatting helpers
- agent/insights.py: refactored to reuse usage_pricing (eliminates
  duplicate pricing table and formatting logic)
- cli.py: status bar with FormattedTextControl fragments, color-coded
  context thresholds (green/yellow/orange/red), enhanced /usage with
  cost breakdown, 1Hz idle refresh for status bar updates
- tests/test_cli_status_bar.py: status bar snapshot, width collapsing,
  usage report with/without pricing, zero-priced model handling
- tests/test_insights.py: verify zero-priced providers show as unknown

Salvage fixes:
- Resolved conflict with voice status bar (both coexist in layout)
- Import _format_context_length from hermes_cli.banner (moved since PR)

Co-authored-by: kshitijk4poor <kshitijk4poor@users.noreply.github.com>

agent/usage_pricing.py

@@ -0,0 +1,134 @@
+from __future__ import annotations
+
+from decimal import Decimal
+from typing import Dict
+
+
+MODEL_PRICING = {
+    "gpt-4o": {"input": 2.50, "output": 10.00},
+    "gpt-4o-mini": {"input": 0.15, "output": 0.60},
+    "gpt-4.1": {"input": 2.00, "output": 8.00},
+    "gpt-4.1-mini": {"input": 0.40, "output": 1.60},
+    "gpt-4.1-nano": {"input": 0.10, "output": 0.40},
+    "gpt-4.5-preview": {"input": 75.00, "output": 150.00},
+    "gpt-5": {"input": 10.00, "output": 30.00},
+    "gpt-5.4": {"input": 10.00, "output": 30.00},
+    "o3": {"input": 10.00, "output": 40.00},
+    "o3-mini": {"input": 1.10, "output": 4.40},
+    "o4-mini": {"input": 1.10, "output": 4.40},
+    "claude-opus-4-20250514": {"input": 15.00, "output": 75.00},
+    "claude-sonnet-4-20250514": {"input": 3.00, "output": 15.00},
+    "claude-3-5-sonnet-20241022": {"input": 3.00, "output": 15.00},
+    "claude-3-5-haiku-20241022": {"input": 0.80, "output": 4.00},
+    "claude-3-opus-20240229": {"input": 15.00, "output": 75.00},
+    "claude-3-haiku-20240307": {"input": 0.25, "output": 1.25},
+    "deepseek-chat": {"input": 0.14, "output": 0.28},
+    "deepseek-reasoner": {"input": 0.55, "output": 2.19},
+    "gemini-2.5-pro": {"input": 1.25, "output": 10.00},
+    "gemini-2.5-flash": {"input": 0.15, "output": 0.60},
+    "gemini-2.0-flash": {"input": 0.10, "output": 0.40},
+    "llama-4-maverick": {"input": 0.50, "output": 0.70},
+    "llama-4-scout": {"input": 0.20, "output": 0.30},
+    "glm-5": {"input": 0.0, "output": 0.0},
+    "glm-4.7": {"input": 0.0, "output": 0.0},
+    "glm-4.5": {"input": 0.0, "output": 0.0},
+    "glm-4.5-flash": {"input": 0.0, "output": 0.0},
+    "kimi-k2.5": {"input": 0.0, "output": 0.0},
+    "kimi-k2-thinking": {"input": 0.0, "output": 0.0},
+    "kimi-k2-turbo-preview": {"input": 0.0, "output": 0.0},
+    "kimi-k2-0905-preview": {"input": 0.0, "output": 0.0},
+    "MiniMax-M2.5": {"input": 0.0, "output": 0.0},
+    "MiniMax-M2.5-highspeed": {"input": 0.0, "output": 0.0},
+    "MiniMax-M2.1": {"input": 0.0, "output": 0.0},
+}
+
+DEFAULT_PRICING = {"input": 0.0, "output": 0.0}
+
+
+def get_pricing(model_name: str) -> Dict[str, float]:
+    if not model_name:
+        return DEFAULT_PRICING
+
+    bare = model_name.split("/")[-1].lower()
+    if bare in MODEL_PRICING:
+        return MODEL_PRICING[bare]
+
+    best_match = None
+    best_len = 0
+    for key, price in MODEL_PRICING.items():
+        if bare.startswith(key) and len(key) > best_len:
+            best_match = price
+            best_len = len(key)
+    if best_match:
+        return best_match
+
+    if "opus" in bare:
+        return {"input": 15.00, "output": 75.00}
+    if "sonnet" in bare:
+        return {"input": 3.00, "output": 15.00}
+    if "haiku" in bare:
+        return {"input": 0.80, "output": 4.00}
+    if "gpt-4o-mini" in bare:
+        return {"input": 0.15, "output": 0.60}
+    if "gpt-4o" in bare:
+        return {"input": 2.50, "output": 10.00}
+    if "gpt-5" in bare:
+        return {"input": 10.00, "output": 30.00}
+    if "deepseek" in bare:
+        return {"input": 0.14, "output": 0.28}
+    if "gemini" in bare:
+        return {"input": 0.15, "output": 0.60}
+
+    return DEFAULT_PRICING
+
+
+def has_known_pricing(model_name: str) -> bool:
+    pricing = get_pricing(model_name)
+    return pricing is not DEFAULT_PRICING and any(
+        float(value) > 0 for value in pricing.values()
+    )
+
+
+def estimate_cost_usd(model: str, input_tokens: int, output_tokens: int) -> float:
+    pricing = get_pricing(model)
+    total = (
+        Decimal(input_tokens) * Decimal(str(pricing["input"]))
+        + Decimal(output_tokens) * Decimal(str(pricing["output"]))
+    ) / Decimal("1000000")
+    return float(total)
+
+
+def format_duration_compact(seconds: float) -> str:
+    if seconds < 60:
+        return f"{seconds:.0f}s"
+    minutes = seconds / 60
+    if minutes < 60:
+        return f"{minutes:.0f}m"
+    hours = minutes / 60
+    if hours < 24:
+        remaining_min = int(minutes % 60)
+        return f"{int(hours)}h {remaining_min}m" if remaining_min else f"{int(hours)}h"
+    days = hours / 24
+    return f"{days:.1f}d"
+
+
+def format_token_count_compact(value: int) -> str:
+    abs_value = abs(int(value))
+    if abs_value < 1_000:
+        return str(int(value))
+
+    sign = "-" if value < 0 else ""
+    units = ((1_000_000_000, "B"), (1_000_000, "M"), (1_000, "K"))
+    for threshold, suffix in units:
+        if abs_value >= threshold:
+            scaled = abs_value / threshold
+            if scaled < 10:
+                text = f"{scaled:.2f}"
+            elif scaled < 100:
+                text = f"{scaled:.1f}"
+            else:
+                text = f"{scaled:.0f}"
+            text = text.rstrip("0").rstrip(".")
+            return f"{sign}{text}{suffix}"
+
+    return f"{value:,}"