docs: correct versions, counts and catalogue entries that had drifted from the code

[TheMeinerLP]

Proposed changes

Stacked on #99 (docs/gitbook-diataxis), so the diff shows only the correction commit. Once #99 merges, retarget this PR to main.

This PR corrects facts in docs/ (except docs/superpowers/) that had drifted from the code. No page was moved, restructured or restyled. Each correction below is checked against the tree at this commit; where a fact could not be checked, it is left unchanged and listed under Open.

Corrections (fact, then evidence)

• Current version 2.1.0 -> 3.0.0 in reference/modules-and-coordinates.md (5 rows), how-to/add-falco-to-your-build.md, tutorials/load-your-first-world-with-falco.md. Evidence: build.gradle.kts:7 (version = "3.0.0"), .release-please-manifest.json.
• BOM contents: the BOM covers three modules, not four. falco-migration is published but not in the BOM, so the how-to now gives it an explicit version. Evidence: falco-bom/build.gradle.kts:5-7; falco-migration is in publishedModules (build.gradle.kts:66).
• Minestom compileOnly: present in falco-anvil, falco-light, falco-instance only. falco-migration and falco-bom declare none. fastutil and flare-fastutil are compileOnly in falco-instance only. Evidence: the falco-*/build.gradle.kts files.
• Renovate: the custom manager in renovate.json matches README.md only, so the docs are not updated by it. The page now says so instead of "cannot reach". Evidence: renovate.json managerFilePatterns.
• ChunkDataException.Reason has seven constants, not six. The five missing ones are added to the reason table with their Javadoc meanings. Evidence: falco-anvil/.../ChunkDataException.java:37-75. RegionFormatException.Reason has five and is still not listed (noted on the page).
• Logging: the INFO line Copied {} to {} before migrating its chunks on disk is added to the level table. Evidence: falco-anvil/.../FalcoAnvilLoader.java:2203.
• SECTIONS_KEY link removed: the constant is private static final, so the link pointed at nothing public. Name and value stay as text. Evidence: FalcoAnvilLoader.java:94.
• Minestom resolved version 2026.06.20-26.1.2 -> 2026.09.12-26.2 in the present-tense build statements: reference/supported-versions.md, contributing/README.md, contributing/dependency-management.md, contributing/documentation-conventions.md, reference/benchmark-catalogue.md, the tutorial snippet. Evidence: settings.gradle.kts (bom = 1.8.7), and ./gradlew --offline :falco-anvil:dependencyInsight --dependency net.minestom:minestom --configuration compileClasspath resolves net.minestom:minestom:2026.09.12-26.2 (by constraint) via mycelium-bom:1.8.7.
• Other pins in the contributing pages and the benchmark catalogue follow settings.gradle.kts: mycelium-bom 1.8.7, adventure-bom 5.2.0, slf4j 2.0.20, fastutil 8.5.19, Cyano 0.7.6, JUnit 6.1.3 (verified offline), ArchUnit 1.5.1.
• Gradle 9.6.1 -> 9.8.1 in contributing/build-setup.md and contributing/README.md. Evidence: gradle/wrapper/gradle-wrapper.properties.
• Module count seven -> eight, and falco-migration is listed as published. Evidence: settings.gradle.kts (eight includes), the eight falco-*/build.gradle.kts files, build.gradle.kts:66.
• Workflow pins @v2.4.0 are replaced by a link to the file that pins the version (.github/workflows/release-please.yml for gradle-publish, .github/workflows/build-pr.yml for gradle-build-pr). The pinned value there is v2.9.0. The pages no longer carry a number that goes stale.
• Benchmark catalogue: nine benchmark classes had no entry. They are added in the existing table format, with methods and @Param values taken from the code and "What it answers" taken from each class Javadoc: AreaPassStageBenchmark (light table), and an Instance table for ChunkComparisonBenchmark, ChunkLookupBenchmark, ChunkResendCostBenchmark, GeneratorCommitBenchmark, LazySectionBenchmark, PaletteIndirectGetBenchmark, SectionAllocationBenchmark (no @Param, shown as "-"), SetBlockContentionBenchmark. All 25 @Benchmark classes in falco-benchmarks/src/jmh now have an entry.
• Heap statement: three classes set no heap flags, not two: AreaVsPerChunkBenchmark, IncrementalVsFullBenchmark, and ChunkLookupBenchmark, which has no @Fork annotation at all. Evidence: grep -rn "@Fork" falco-benchmarks/src/jmh. The same correction is applied to the "One heap gap" paragraph of reference/measured-results.md.

Deliberately not changed

• reference/measured-results.md, how-to/reproduce-a-published-measurement.md: these state the Minestom and JMH setup the published numbers were measured with. That is history, not the current build.
• project-record/project-status.md:413 ("the 2.1.0 release"): historical.
• Explanation pages that cite Minestom source lines "at 2026.06.20-26.1.2" (see Open).

Open (not changed, needs its own pass)

1. Minestom source citations. About 20 explanation and research pages cite Minestom 2026.06.20-26.1.2 source lines, and some state mycelium-bom 1.7.2 as the current pin in present tense (for example explanation/why-a-custom-light-engine.md:21, explanation/why-falco-instance-exists.md:30, explanation/why-a-second-anvil-loader.md:18, explanation/what-a-measurement-here-means.md:542,871, explanation/how-the-concurrency-design-works.md:13, explanation/what-the-benchmarks-establish.md:149, explanation/choosing-between-falco-and-the-built-in-loader.md:8,13, explanation/comparing-the-light-engine-with-minestoms.md:325, explanation/how-the-light-engine-works.md:206). Line numbers have to be re-read against 2026.09.12-26.2 before these can move. Not done here.
2. Adventure/fastutil of the current Minestom. Whether 2026.09.12-26.2 declares adventure-nbt 5.1.1 and fastutil 8.5.18 (as 2026.06.20 did) was not re-checked. dependency-management.md now says so explicitly. The Minestom POM is not in the local Gradle cache.
3. Open list in project-record/project-status.md: the entries "Resolved in perf(light): keep the opacity tables of a chunk with its light #34" (line 799) and "Resolved in fix(anvil): refuse a full chunk that carries no sections #49" (line 901) sit under ## Open. Reported only, for a follow-up PR.
4. CONTRIBUTING.md (repo root, outside docs/): historical sentence about mycelium-bom:1.7.2 "up to 2.1.0". Left as it is.
5. benchmark-catalogue.md "mycelium-bom ... covers adventure, minestom, cyano, junit and mockito only": checked against the cached mycelium-bom 1.8.5 POM (adventure-text-minimessage, cyano, junit-bom, minestom, mockito-*); the 1.8.7 POM itself was not read.

Checks

• Link checker run against this worktree (copy of the scratchpad check.py with ROOT taken from argv, since the original hard-codes another worktree): scanned 62 files, 855 relative links/anchors, PROBLEMS: none, exit 0.
• Remaining 2\.1\.0|9\.6\.1|v2\.4\.0 in docs/ (excluding superpowers): only project-record/project-status.md:413 (historical).
• No tests or Gradle build changed; this is a docs-only change. ./gradlew build was not run.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance change (behaviour unchanged, cost changed)
• Documentation Update (if none of the other choices apply)

Checklist

• The title of this pull request is a Conventional Commit
• I have added necessary documentation (if appropriate)
• ./gradlew build is green locally (not run: docs-only change)

Stacked on #99.

https://claude.ai/code/session_01Q6AxU7jRLmNPHdwg2GpasT