feat(dashboard): track real API call count per session

Adds schema v7 'api_call_count' column. run_agent.py increments it by 1
per LLM API call, web_server analytics SQL aggregates it, frontend uses
the real counter instead of summing sessions.

The 'API Calls' card on the analytics dashboard previously displayed
COUNT(*) from the sessions table — the number of conversations, not
LLM requests. Each session makes 10-90 API calls through the tool loop,
so the reported number was ~30x lower than real.

Salvaged from PR #10140 (@kshitijk4poor). The cache-token accuracy
portions of the original PR were deferred — per-provider analytics is
the better path there, since cache_write_tokens and actual_cost_usd
are only reliably available from a subset of providers (Anthropic
native, Codex Responses, OpenRouter with usage.include).

Tests:
- schema_version v7 assertion
- migration v2 -> v7 adds api_call_count column with default 0
- update_token_counts increments api_call_count by provided delta
- absolute=True sets api_call_count directly
- /api/analytics/usage exposes total_api_calls in totals

hermes_cli/web_server.py

@@ -2189,7 +2189,8 @@ async def get_usage_analytics(days: int = 30):
                    SUM(reasoning_tokens) as reasoning_tokens,
                    COALESCE(SUM(estimated_cost_usd), 0) as estimated_cost,
                    COALESCE(SUM(actual_cost_usd), 0) as actual_cost,
-                   COUNT(*) as sessions
+                   COUNT(*) as sessions,
+                   SUM(COALESCE(api_call_count, 0)) as api_calls
             FROM sessions WHERE started_at > ?
             GROUP BY day ORDER BY day
         """, (cutoff,))
@@ -2200,7 +2201,8 @@ async def get_usage_analytics(days: int = 30):
                    SUM(input_tokens) as input_tokens,
                    SUM(output_tokens) as output_tokens,
                    COALESCE(SUM(estimated_cost_usd), 0) as estimated_cost,
-                   COUNT(*) as sessions
+                   COUNT(*) as sessions,
+                   SUM(COALESCE(api_call_count, 0)) as api_calls
             FROM sessions WHERE started_at > ? AND model IS NOT NULL
             GROUP BY model ORDER BY SUM(input_tokens) + SUM(output_tokens) DESC
         """, (cutoff,))
@@ -2213,7 +2215,8 @@ async def get_usage_analytics(days: int = 30):
                    SUM(reasoning_tokens) as total_reasoning,
                    COALESCE(SUM(estimated_cost_usd), 0) as total_estimated_cost,
                    COALESCE(SUM(actual_cost_usd), 0) as total_actual_cost,
-                   COUNT(*) as total_sessions
+                   COUNT(*) as total_sessions,
+                   SUM(COALESCE(api_call_count, 0)) as total_api_calls
             FROM sessions WHERE started_at > ?
         """, (cutoff,))
         totals = dict(cur3.fetchone())