fix: bound wiki reduce input growth

[Hughhhhcoder]

Description

Bound the aggregate trim-eligible inputs sent to WikiPageModify with an explicit WikiConfig byte budget. This prevents hub-page reduce prompts from growing without limit while preserving deletion instructions and keeping stable source/page context where possible.

Type of Change

• 🐛 Bug fix
• 🧪 Test
• 📚 Documentation update

Related Issue

Fixes #2718

Testing

• go test ./internal/application/service -run TestTrimWikiReduceInputsBoundsConfiguredContext -count=1
• go test ./internal/application/service -run "TestTrimWikiReduceInputsBoundsConfiguredContext|TestGenerateWithTemplateSetsMaxTokens" -count=1
• go test ./internal/application/service -count=1
• go test ./internal/types ./internal/application/service -count=1
• git diff --check

go test ./... was also run; it reached the repository test execution but stopped because the host filesystem ran out of space (no space left on device), with no assertion failure reported. The focused and changed-package tests pass.

Checklist

• git diff --check origin/main...HEAD passes
• Changed source files are formatted
• Targeted tests pass
• Full-repository check: documented above as environment-blocked
• Self-reviewed the code
• Added regression coverage
• Updated generated documentation

[Hughhhhcoder]

The latest App and Go Lint pull-request workflow runs are completed with action_required. Could a maintainer approve the workflows when convenient so CI can run? The CodeCC scan is passing and the local focused validation is complete.