Extends the FilterBar query language with a json[field] <op> value
comparison, parsed by filter_parser.pest/rs alongside metric[param],
and evaluated in engine.rs by parsing each line as JSON at query time
(lines that aren't valid JSON, or lack the field, simply don't match).
Also wired into alerts.rs since json[field], like regex/sequence/
timestamp, only needs the line's own text.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o
Introduces a standalone src/filter_parser.rs module (no dependency on
engine/index types) that parses the FilterBar query language into a
FilterExpr AST using a pest grammar (src/filter_parser.pest). Supports
regex("...") searches, metric_name[param] <op> value comparisons,
reserved sequence/timestamp metrics, and and/or combinators with
correct precedence (and binds tighter than or) and parenthesized
sub-expressions. Evaluation against real log data is left to a later
integration ticket.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o
