docs: prepare changelog for jinjava 2.8.4 release

[jasmith-hs]

Description

Adds the 2.8.4 release notes (dated 2026-07-24) to the top of CHANGES.md on the master-2.8.x maintenance line — the branch the 2.8.4 release actually builds from (currently 2.8.4-SNAPSHOT). This changelog is authored by Claude Code.

The entries cover every user-facing PR merged into master-2.8.x since 2.8.3 shipped on 2026-02-02 — largely backports of 3.0-line fixes/features that consumers still pinned to the 2.8.x line need:

• Configurable multi-character delimiters (feat: add StringTokenScannerSymbols for configurable multi-character delimiters (fixes #195) #1305)
• Backslash as an escape character only inside quoted strings, matching Jinja2 (fix: treat backslash as escape character only inside quoted strings, matching Jinja2 behaviour (fixes #1304) #1306)
• keepTrailingNewline option matching Python Jinja2's default (Add keepTrailingNewline option to LegacyOverrides to match Python Jinja2 default behaviour #1311)
• Auto-convert Integer to Long in set filters (Auto-convert Integer to Long in set filters (3.0) #1308)
• Boolean parameter on withUnwrapRawOverride (feat: add boolean parameter to withUnwrapRawOverride #1313)
• BuiltinFeatures (Introduce BuiltinFeatures #1289)
• Preserve block tags for reconstruction/execution order (fix: Preserve block tags to preserve reconstruction/execution order #1312)
• Fix RenderFilter handling of deferred values (fix(eager): Fix RenderFilter's handling of deferred values #1258)
• Eager: use isResolvableObject before building hashcode (fix(eager): Use isResolvableObject instead of contains before trying to build hashcode #1286)
• Don't require explicitly pushing the JinjavaInterpreter (refactor: Don't require explicitly pushing JinjavaInterpreter when using it directly #1285)

A pom publish-location revert (#1283) was excluded as non-user-facing.

Notes

• Companion PR against master: docs: prepare changelog for jinjava 2.8.4 release #1326 (same changelog entry, matching prior changelog-prep convention).
• Bundled backports feat: add StringTokenScannerSymbols for configurable multi-character delimiters (fixes #195) #1305/fix: treat backslash as escape character only inside quoted strings, matching Jinja2 behaviour (fixes #1304) #1306/Add keepTrailingNewline option to LegacyOverrides to match Python Jinja2 default behaviour #1311 (landed on 2.8.x via feat: backport configurable delimiters, backslash handling & keepTrailingNewline to 2.8.x #1325) are linked to their originating PRs for the clearest descriptions; Auto-convert Integer to Long in set filters (3.0) #1308/fix: Preserve block tags to preserve reconstruction/execution order #1312/feat: add boolean parameter to withUnwrapRawOverride #1313 likewise link to the originating PRs rather than their 2.8.x backports (Auto-convert Integer to Long in set filters (2.8.x) #1309/fix: Backport block tag preservation fix to 2.8.x (#1312) #1315/feat: add boolean parameter to withUnwrapRawOverride (2.8.x) #1314).

This PR description was authored by Claude Code.