feat(mvn): add Maven filter module — test, build, dependency:tree

[mariuszs]

Summary

Adds a Rust filter module for Maven (mvn) commands, replacing the old mvn-build.toml declarative filter with a state-machine parser that achieves 90-99%+ token savings on real-world output.

Subcommands

• mvn test — State-machine parser (Preamble → Testing → Summary → Done) extracts failure names, assertion details, and run counts. Caps output to 10 failures with truncated lines. Handles multi-module builds, ANSI-heavy output, and large suites (3000+ tests).
• mvn build (compile/package/clean/install/verify) — Line filter strips [INFO] noise, download progress, and Testcontainers chatter. Keeps errors, BUILD result, and total time.
• mvn dependency:tree — Strips boilerplate, "omitted for duplicate" lines, and "version managed from" annotations. Preserves tree structure and conflict markers.
• Other goals — Streaming passthrough via cmd.status() (safe for long-running goals like spring-boot:run), with usage tracking.

Routing

Clap Mvn sub-enum with Test, Build, DepTree, and #[command(external_subcommand)] Other variants. Build-like goals in Other are auto-routed to the build filter. Auto-detects mvnw wrapper.

Token savings (measured on real project logs)

mvn test

Scenario	Tests	Lines in	Savings
Single-module, all pass	183 OK	41	97%
Real Spring Boot project, all pass	959 OK, 9 skipped	10,070	100%
Single-module, 2 assertion failures	5 run, 2 failed	3,380	99.7%
Multi-module (4 modules), JGit errors	860 run, 4 errors	7,039	99.7%
Large suite, mixed errors (assertions + compilation)	3,262 run, 23 failed	40,760	99.9%

mvn dependency:tree

Scenario	Lines in	Savings
Simple project (4 direct deps)	23	~40%
Spring Boot project (36 direct deps, 652 tree lines)	652	60%+

Output examples

Success: mvn test: 950 passed, 9 skipped (01:32 min)

Failure:

mvn test: 5 run, 2 failed (23.819 s)
BUILD FAILURE

Failures:
1. EmailParserTest.should_extract_domain_from_email
   org.opentest4j.AssertionFailedError:
   expected: "broken.example.com"
   but was: "user.example.com"
2. ScoreTypeTest.shouldMapToRole
   org.opentest4j.AssertionFailedError:
   expected: "app:BROKEN"
   but was: "app:all"

Tests

21 tests against 8 real-world fixtures (1310 lines total):

• Pass/fail/multi-module/large suite/ANSI scenarios for mvn test
• Simple/conflict/large dependency trees with duplicate stripping
• Token savings assertions (≥60-95% depending on scenario)
• Edge cases: empty input, no test section

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