docs(mvn): add Java ecosystem README, update CHANGELOG and main README

Add missing documentation required by CONTRIBUTING.md for new Rust
filter modules: ecosystem README, CHANGELOG entry, and Maven commands
in the main README savings table and commands reference.

Author: mariuszs

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Features
+
+* **mvn:** add Maven (Java) filter module — test, build, dependency:tree ([#1089](https://github.com/rtk-ai/rtk/pull/1089))
+
 ### Bug Fixes
 
 * **git:** remove `-u` short alias from `--ultra-compact` to fix `git push -u` upstream tracking ([#1086](https://github.com/rtk-ai/rtk/issues/1086))

README.md

@@ -47,6 +47,7 @@ rtk filters and compresses command outputs before they reach your LLM context. S
 | `git log` | 5x | 2,500 | 500 | -80% |
 | `git add/commit/push` | 8x | 1,600 | 120 | -92% |
 | `cargo test` / `npm test` | 5x | 25,000 | 2,500 | -90% |
+| `mvn test` | 3x | 30,000 | 300 | -99% |
 | `ruff check` | 3x | 3,000 | 600 | -80% |
 | `pytest` | 4x | 8,000 | 800 | -90% |
 | `go test` | 3x | 6,000 | 600 | -90% |
@@ -179,6 +180,7 @@ rtk go test                     # Go tests (NDJSON, -90%)
 rtk cargo test                  # Cargo tests (-90%)
 rtk rake test                   # Ruby minitest (-90%)
 rtk rspec                       # RSpec tests (JSON, -60%+)
+rtk mvn test                    # Maven tests (-99%)
 rtk err <cmd>                   # Filter errors only from any command
 rtk test <cmd>                  # Generic test wrapper - failures only (-90%)
 ```
@@ -195,6 +197,8 @@ rtk cargo clippy                # Cargo clippy (-80%)
 rtk ruff check                  # Python linting (JSON, -80%)
 rtk golangci-lint run           # Go linting (JSON, -85%)
 rtk rubocop                     # Ruby linting (JSON, -60%+)
+rtk mvn build                   # Maven build (-90%)
+rtk mvn dependency:tree         # Maven dependency tree (-60%+)
 ```
 
 ### Package Managers

src/cmds/java/README.md

@@ -0,0 +1,14 @@
+# Java Ecosystem
+
+> Part of [`src/cmds/`](../README.md) — see also [docs/contributing/TECHNICAL.md](../../../docs/contributing/TECHNICAL.md)
+
+## Specifics
+
+- **mvn_cmd.rs** handles Maven (`mvn`) and Maven Wrapper (`mvnw`) commands
+- Auto-detects `mvnw` wrapper in project root; falls back to system `mvn`
+- `mvn test` uses a state-machine parser (Preamble → Testing → Summary → Done) for 97-99%+ savings on real-world output
+- `mvn build` (compile/package/clean/install/verify) uses line filtering to strip `[INFO]` noise, download progress, and plugin chatter (jOOQ codegen, Liquibase, npm/React builds)
+- `mvn dependency:tree` strips "omitted for duplicate" lines, "version managed from" annotations, and collapses deep transitive branches
+- Unsupported goals stream via `cmd.status()` passthrough (safe for long-running goals like `spring-boot:run`)
+- Routing via Clap sub-enum with `#[command(external_subcommand)] Other` for unknown goals
+- Build-like goals received as `Other` are auto-routed to the build filter