Cover custom log_format URI variables in botlog

[sergeyfast]

Summary

Follow-up to #9. After rolling out the query-params fix, real-world logs showed two formats the priority chain missed:

1. Key=value formats with separate $uri and $args fields (uriPath="$uri" uriQuery="$args") — bot-log got path-only URIs, the original bug came back for this style.
2. Hybrid combined + key=value logging both "$request" and ru="$request_uri" plus u="$uri" (post-rewrite internal path).

Changes

• Extract resolveURI(get func(string) string) walking nginx URI variables in priority order: $request_uri → $request → $uri (+ optional $args / $query_string). Single source of truth for both gonx text path and JSON map path. Closures stay stack-allocated (func literal does not escape per gcflags -m).
• Add joinPathArgs(path, args) to recombine split fields.
• Always strip query before normalizePath in every branch — defense in depth so utm/session params can never reach Prometheus uri labels even if an operator logs $request_uri under the uri field name by mistake.

Test plan

• make fmt lint test — 0 issues, all green
• New table cases in TestParsedLine_RawURIUnnormalized (13 total):
  • separate $uri + $args (the immediate regression)
  • empty $args (must not append ?)
  • $query_string alias
  • $request_uri directly
  • hybrid format with internal rewrite ($request_uri wins over post-rewrite $uri)
  • hybrid format with comma-rich query strings (gonx quoted-value handling)
  • metric URI stays query-free even if $uri carries query (defensive)
  • JSON map path with base64 signed-URL token (cardinality collapse)
• Smoke on staging: verify bot-log events from operators using non-$request log formats now carry the full URI