Add eBay Browse API integration with daily call quota

eBay marketplaces are now polled through eBay's official Buy > Browse API (client-credentials OAuth2) instead of an Apify scraper actor; Apify still handles Yahoo JP and Mercari. Browse API calls are tracked per day in a new ebay_api_usage table and capped (default 5000, configurable) on eBay's Pacific-time reset clock, so polling halts before the limit is hit. Credentials live in config.toml [ebay] and are overridable via /settings, which also surfaces the day's running call count.

Also carries the server.secure_cookies config plumbing (field, accessor, example) consumed by the following commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

config.toml.example

@@ -1,6 +1,11 @@
 [server]
 port = 8080
 db_path = "./veola.db"
+# Sets the Secure attribute on the session cookie. Leave true for any
+# HTTPS-reachable deployment, including behind a TLS-terminating proxy such as
+# Traefik. Defaults to true if omitted; set false only for local plain-HTTP
+# development on a non-localhost address.
+secure_cookies = true
 
 [security]
 # Both must be at least 32 bytes and different from each other.
@@ -31,6 +36,21 @@ yahoo_auctions_jp      = "meron1122/zenmarket-scraper"
 yahoo_auctions_jp_sold = ""  # no known verified sold-listings actor for Yahoo JP
 mercari_jp             = "cloud9_ai/mercari-scraper"
 
+# eBay's official Buy > Browse API. When client_id and client_secret are set,
+# eBay marketplaces (ebay.com, ebay.co.uk, ...) are polled through this API
+# instead of an Apify scraper actor; Apify still handles Yahoo JP and Mercari.
+# client_id is the App ID and client_secret is the Cert ID from your eBay
+# developer keyset. Both can also be set/overridden at runtime via /settings.
+# environment is "production" (default) or "sandbox".
+# daily_call_limit caps Browse API calls per day on eBay's own quota clock
+# (midnight US Pacific); once hit, eBay polling halts until the next reset.
+# 5000 is the standard Browse API allowance; set a negative value to disable.
+[ebay]
+client_id        = ""
+client_secret    = ""
+environment      = "production"
+daily_call_limit = 5000
+
 [ntfy]
 base_url      = "https://ntfy.yourdomain.com"
 default_topic = "veola"