Fix #12571: Build Report Foundation — structured report, console modes, warning control

[gnodet]

Summary

Implements the build output overhaul proposed in #12571: a structured BuildReport data model with JSON persistence, a DiagnosticCollector for deduplicated warning summaries, four --console modes (plain, rich, machine, verbose), a --warning-mode CLI flag, automatic Log.warn() interception for Maven 3 plugin warnings, and per-key diagnostic suppression.

What's included

Structured Build Report

• BuildReport → ModuleReport → MojoReport data model in maven-api-core with id() and findModule()/findMojo() lookup methods
• Per-mojo and per-module log capture using structured LogEvent
• FailureReport with timestamp, exception type, and stack trace
• BuildReportCollector (EventSpy, @Named @Singleton) — captures lifecycle events
• BuildReportJsonWriter — hand-written JSON serializer (no library dependency)
• Persists target/build-report.json at session end
• API lives in org.apache.maven.api.build.report sub-package

DiagnosticCollector + Warning Summary

• Diagnostic / DiagnosticCollector / DiagnosticSummary API
• DefaultDiagnosticCollector — thread-safe (ConcurrentHashMap + LongAdder), dedup by key, capped at 1000
• Deduplicated warning summary printed at end of build with counts, suggestions, doc URLs
• Diagnostics written to build-report.json

Console Modes (--console)

Flag	Behavior
--console=auto (default)	CI → plain; TTY → rich; otherwise → verbose
--console=plain	One line per module, no ANSI — auto-selected in CI
--console=rich	JLine status bar with live reactor progress, parallel-build aware
--console=verbose	Full mojo-level output (Maven 4.0 default)
--console=machine	JSON lines — one typed event per line, designed for tools and LLM agents

Plain mode: compact footer, no ANSI control sequences.
Rich mode: live Status bar showing active modules, [n/total] progress, elapsed time, download progress. Falls back gracefully on dumb terminals.
Machine mode: one JSON object per line with typed "event" field and ISO-8601 timestamps. Events: build.started/finished, module.started/succeeded/failed/skipped, mojo.*, fork.*, transfer.*.

Warning Mode, Log Interception, Diagnostic Suppression

Flag	Behavior
--warning-mode=summary (default)	Collect and show deduplicated summary at end
--warning-mode=all	Show inline + summary
--warning-mode=none	Suppress diagnostic summary
--warning-mode=fail	Show summary + fail build if warnings exist

• Log.warn() interception — auto-feeds Maven 3 plugin WARN-level output into DiagnosticCollector via synthetic dedup keys (auto:<LoggerSuffix>:<hexHash>), with file-coordinate stripping so the same warning from different files deduplicates
• -Dmaven.diagnostic.suppress=<key> — suppress diagnostics by exact key or prefix wildcard (auto:*)

What's NOT included (separate work)

• Core plugin migration (maven-compiler-plugin, maven-enforcer-plugin, maven-surefire-plugin, maven-dependency-plugin reporting structured Diagnostic objects)
• mvn build-report:show plugin

Tests

91 unit tests across 10 test classes covering report assembly, JSON serialization, diagnostic dedup/suppression/concurrency, all console modes, and all warning modes. Integration tests that assert on verbose log output explicitly set --console=verbose to work correctly under CI auto-detection.