Improve Java Javadocs for core TsFile components

[wangx0502]

Summary

Improve and clarify Java comments and Javadocs for core TsFile components.

Changes

• Clarify TsFile file-header and version-format descriptions.
• Improve documentation for Page, Chunk, ChunkGroup, and metadata index structures.
• Document aligned and non-aligned writing behavior.
• Clarify page statistics, lazy metadata loading, filtering, deletion, and chunk merging
  semantics.
• Add algorithm notes for encoding and compression components.
• Fix outdated or misleading comments.
• Add missing class-level documentation for important public APIs.

This change is documentation-only and does not intentionally change runtime behavior.

Validation

• git diff --check
• ./mvnw -Pwith-java spotless:check
• ./mvnw -Pwith-java -Dmaven.test.skip=true verify

The production code compilation, packaging, Checkstyle, Spotless, and RAT checks passed.

Full test compilation should be tracked separately because some existing test sources
reference package names that do not match the current source layout.