feat(landing): log parsing guide - #1578

🟡 Confidence 6/10 · needs attention. Held at 6 because a correctness warning is open.
_{1 warning −1 · tests not needed · risk medium · 2 defects fixed in earlier rounds}

Adds the /guides/log-parsing page, six raw Collector configs, two screenshots and two highlight languages. The build-time regex guard holds and the configs match their sample lines; one claim about query strings is wrong and should be fixed before merge.

• log-parsing.astro builds the nginx regex from its colored segments and splits nginx.yaml on it, so a mismatch breaks the build
• guide-highlight.ts gains an otel-debug language and single-quoted strings in shell
• Each format ships as its own file under _log-parsing/, with file_log/otlp_http names and a debug.yaml overlay
• The guide is listed in guides/index.astro and llms.txt.ts

Findings

Say the fields are dropped from the attributes but stay in the record's body, or add a `set(log.body, ...)`/`move` that replaces the raw line.

Fixed since the last review

• ✅ F2 · Card says 14 min read, the guide header says 10

Production impact

_{92bcc7a · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}