feat(log-query): add 'jmespath:' filter syntax as alternative to jq for JSON log processing

[sarub0b0]

Summary

This PR adds JMESPath filter syntax (jmespath:) to the log query feature as an alternative to the jq: filter. JMESPath provides a different JSON query language that some users may find more intuitive for certain use cases.

Motivation

• Issue Enhance JSON logging #809 requests support for both jq and JMESPath filter syntaxes
• JMESPath offers a simpler, more declarative syntax for common JSON queries
• Provides users with choice between two complementary JSON query languages

Changes

New Query Syntax

• jmespath:<expression> - Filter JSON logs using JMESPath expressions
• Aliases: jmes:, jm:
• Example: pod:api log:error jmespath:message or pod:api jm:data.userId

Implementation Details

• Extends the existing JsonFilter enum with JMESPath variant alongside Jq
• Adds JMESPathProgram struct to hold compiled expressions with 'static lifetime
• Adds jmespath_expression parser to handle the new syntax with three aliases
• JMESPath expressions are compiled at parse time using the jmespath crate (v0.4.0 with sync feature)
• Mutually exclusive with jq: filter (last one specified wins, consistent with other single-value filters)
• Adds FilterError::JMESPathCompile for compilation errors (holds JmespathError directly)

Error Handling

• Parse errors show helpful messages with syntax guidance
• Runtime evaluation errors display the error and fall back to showing the original log line
• Serialization errors are caught and handled gracefully
• Compilation errors are caught early during query parsing

Query Compatibility

• Works alongside existing filters: log: / !log:, pod:, container:, label selectors, etc.
• Only one JSON filter (jq or jmespath) can be active at a time

Testing

Added 22 comprehensive tests covering:

Parser tests (9 tests):

• jmespath:, jmes:, and jm: syntax variants (5 test cases)
• Integration with attribute parser (3 test cases)
• Integration with parse_attributes (1 test case)

Filter tests (8 tests):

• Valid JMESPath expression compilation
• Complex expressions (array projections, object restructuring)
• Invalid syntax handling
• Combination with other filters (pod, log, container)
• Multiple JMESPath filters (last one wins)
• Display trait formatting
• Mutual exclusivity with jq filter

LogCollector tests (6 tests):

• Field extraction from JSON logs
• Data restructuring with object literals
• Non-JSON input handling (returns raw log)
• Pretty print integration
• Error handling (nonexistent fields return null)
• Array projection queries

All 491 tests passing (469 existing + 22 new)

Documentation

• README updated with JMESPath query syntax, aliases, and usage examples
• Help dialog updated to include jmespath:<expr> with aliases in the query reference

Commits

1. feat: add jmespath dependency for JSON log filtering
2. feat: implement jmespath filter for JSON log processing
3. docs: add jmespath filter to log query help dialog
4. docs: add jmespath filter documentation to README

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Related: #809
Follows: #841 (jq filter implementation)