chore(log): cap container log growth and echo the resolved config

P2 of the logging plan (the README recipe landed with the code change):

- `docker-compose.yml.example`: one `x-logging` anchor applied to all three
  services. json-file grows without limit by default, so a long-running bot
  and the proxy in front of it fill the disk; capped at 10m × 3 files.
- The startup `config:` line now reports what the process actually resolved —
  the state DB path (a mistyped `DATA_DIR` or a surprising CWD was invisible
  until it bit), both TTLs, the caption-quote setting (`off` rather than a bare
  `0`) and whether a proxy is configured. The proxy URL is never printed (it
  may embed credentials) and admin ids — chat identifiers — stay at `debug`.

Verified: `docker compose config -q` accepts the file, and a scripted fake-API
run shows `caption quote off` / `link cache TTL 3600s` under overrides,
`proxy=yes` with no credential in any line, and the ids at `debug` only.

crates/xmedia-bot/src/main.rs

@@ -67,11 +67,27 @@ async fn main() {
         log::warn!("failed to register commands: {e}");
     }
 
+    // The effective tunables, so an operator can see what the process actually
+    // resolved (a mistyped DATA_DIR or a forgotten TTL override is otherwise
+    // invisible until it bites). The proxy URL is never printed — it may embed
+    // credentials — and admin ids are chat identifiers, so they stay at debug.
+    let quote_chars = match CONFIG.caption_quote_text_chars {
+        0 => "off".to_string(),
+        n => format!("{n} chars"),
+    };
     log::info!(
-        "config: {} admin(s), edit-message TTL {}s",
+        "config: {} admin(s), state {}, edit-message TTL {}s, link cache TTL {}s, caption quote {quote_chars}, proxy={}",
         CONFIG.admin_ids.len(),
-        CONFIG.edit_message_ttl.as_secs()
+        crate::handlers::db_path().display(),
+        CONFIG.edit_message_ttl.as_secs(),
+        CONFIG.link_cache_ttl.as_secs(),
+        if std::env::var("TELOXIDE_PROXY").is_ok() {
+            "yes"
+        } else {
+            "no"
+        }
     );
+    log::debug!("config: admin ids {:?}", CONFIG.admin_ids);
 
     // Queue worker: handles typed tasks, dead-letters failed sends to the
     // task's chat. Both closures use the shared context (the queue requires