[docs] Restructure primary-key table documentation and diagrams

[JingsongLi]

Purpose

The primary-key table guides mix conceptual introductions, configuration details, and long examples, making it difficult to choose a table layout or follow update behavior. Reorganize the existing pages into a reading path covering data layout, updates and changelogs, compaction and querying, and advanced features.

• Add decision tables and concrete SQL examples, and clarify ordering, partial-update NULL and retraction behavior, aggregation, changelog production, deletion vectors, and index coverage against the current implementation.
• Replace bitmap references in these guides with editable SVG diagrams and add diagrams for sequence groups, index coverage, and BLOB lifecycle (10 SVGs in total).
• Fold lengthy reference examples, remove duplicated explanations, preserve page URLs and relevant legacy anchors, and repair the Concepts footer link.

Tests

• COREPACK_ENABLE_AUTO_PIN=0 yarn build: production documentation build and REST OpenAPI validation pass on the updated upstream baseline.
• Browser checks: all 15 primary-key pages, 177 internal links, SVG loading, legacy anchors, SQL tabs, and expandable examples pass.
• Mobile layout checks at 390 px: overview, sequence/row-kind, and partial-update pages have no page-wide horizontal overflow.
• All 10 SVGs pass XML, viewBox, title, and description checks; rendered diagrams were visually inspected.
• git diff --check passes.

SQL examples were checked against the implementation; they were not executed in Flink. This PR changes documentation and static assets only.

[leaves12138]

Reviewed at 5b898f3. One configuration-semantics correction is needed before approval; see the inline comment about the effective default in gentle lookup compaction.

Independent validation passed:

• Production documentation build and REST OpenAPI validation.
• All 175 unique internal body links/anchors across the 15 changed documentation pages.
• Preservation of all 15 primary-key sidebar document IDs.
• Browser checks of all 15 pages: image loading, SQL tabs, expandable examples, 390 px mobile width, and no JavaScript page errors.
• All 10 SVGs: XML metadata, rendered text bounds, and visual inspection.

The semantic review used the implementation and existing test assertions at this head. SQL examples and Java/engine tests were not executed.

[leaves12138]

LGTM. Re-reviewed at 5c5f2d1.

The previous finding is fixed: gentle lookup compaction now correctly documents the effective default of twice the sorted-run compaction trigger (10 with defaults), the minimum applied to an explicit interval, and which selection attempts are counted. I also checked the new force-lookup, radical/gentle, and non-lookup compaction.force-up-level-0 explanations against the implementation.

The only change since my previous review is this compaction guide update. No additional findings.

Revalidation on the updated head:

• Production documentation build and REST OpenAPI validation pass with a fresh dependency installation.
• All 175 unique internal body links/anchors across the 15 primary-key pages resolve; sidebar document IDs and SVG metadata checks pass.
• The updated compaction page passes browser rendering, image loading, mobile-width, and JavaScript-error checks.

SQL examples and Java/engine tests were not executed; this remains a documentation-only change.