opencode prices and Go limits, settings out of .env

- Fetch prices for opencode (Zen and Go) incl. limits, image input, reasoning,
  long-context tiers and peak-hour/date factors; costs apply them per request
- Record the cost opencode reports per response; track Go allowance in 5h/7d/month
  windows against a provider plan limit (budget table, status overlay)
- Settings → Config file: move values of ${NAME} references into the config
- Examples, presets and forms keep keys in the config instead of .env

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/store.rs

@@ -162,6 +162,7 @@ impl Store {
             ("usage", "user_id", "ALTER TABLE usage ADD COLUMN user_id TEXT"),
             ("users", "monthly_quota", "ALTER TABLE users ADD COLUMN monthly_quota REAL"),
             ("jobs", "webhook_secret", "ALTER TABLE jobs ADD COLUMN webhook_secret TEXT"),
+            ("usage", "allowance", "ALTER TABLE usage ADD COLUMN allowance REAL"),
         ] {
             let exists: bool = conn
                 .prepare(&format!("SELECT 1 FROM pragma_table_info('{table}') WHERE name = ?1"))?
@@ -331,6 +332,8 @@ pub struct UsageRecord {
     pub error: bool,
     /// User to bill when there is no session (CLI requests); else the session owner.
     pub user_id: Option<String>,
+    /// opencode Go: share of the plan's usage limits (USD), as reported by the provider.
+    pub allowance: Option<f64>,
 }
 
 /// Aggregation SQL shared by all statistics queries.
@@ -376,13 +379,14 @@ impl Store {
         conn.execute(
             "INSERT INTO usage (ts, session_id, root_session_id, provider, model, agent,
                 input_tokens, output_tokens, cache_read_tokens, cache_write_tokens,
-                ttft_ms, duration_ms, cost, error, user_id)
+                ttft_ms, duration_ms, cost, error, user_id, allowance)
              VALUES (?1,?2,?3,?4,?5,?6,?7,?8,?9,?10,?11,?12,?13,?14,
-                COALESCE(?15, (SELECT owner_id FROM sessions WHERE id = ?3)))",
+                COALESCE(?15, (SELECT owner_id FROM sessions WHERE id = ?3)), ?16)",
             params![
                 u.ts, u.session_id, u.root_session_id, u.provider, u.model, u.agent,
                 u.input_tokens as i64, u.output_tokens as i64, u.cache_read_tokens as i64,
-                u.cache_write_tokens as i64, u.ttft_ms as i64, u.duration_ms as i64, u.cost, u.error as i64, u.user_id
+                u.cache_write_tokens as i64, u.ttft_ms as i64, u.duration_ms as i64, u.cost, u.error as i64, u.user_id,
+                u.allowance
             ],
         )?;
         Ok(())
@@ -886,6 +890,12 @@ impl Store {
 
 impl Store {
     /// Cost per provider since `from` (ms).
+    /// opencode Go: sum of reported allowance of one provider since `from` (ms).
+    pub fn allowance_since(&self, provider: &str, from: i64) -> Result<f64> {
+        let conn = self.conn.lock().unwrap();
+        Ok(conn.query_row("SELECT COALESCE(SUM(allowance), 0) FROM usage WHERE provider = ?1 AND ts >= ?2", params![provider, from], |r| r.get(0))?)
+    }
+
     pub fn cost_by_provider(&self, from: i64) -> Result<std::collections::BTreeMap<String, f64>> {
         let conn = self.conn.lock().unwrap();
         let mut stmt = conn.prepare("SELECT provider, COALESCE(SUM(cost), 0) FROM usage WHERE ts >= ?1 GROUP BY provider")?;