docs: Add doc for features: row based spill, adaptive hash partition, memory management pushdown

[wangxinshuo-bolt]

What problem does this PR solve?

Issue Number: close #695

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🚀 Performance improvement (optimization)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🔨 Refactoring (no logic changes)
• 🔧 Build/CI or Infrastructure changes
• 📝 Documentation only

Description

1. Adds a blog explaining why Bolt moved off-heap memory reservation, repayment, spill, and OOM decisions into the Bolt side. It also covers the follow-up RSS quota calibration mechanism, which uses process RSS feedback to reduce premature spill and OOM when logical quota usage is higher than actual resident memory usage.
2. Adds a blog describing row-based spill for operators whose execution state is already row-oriented. The post explains how writing RowContainer-backed state directly to disk can reduce column-row conversion, serialization, restore, and merge overhead.
3. Adds a blog explaining how HashJoin spill partition counts can be adjusted using runtime row-count information. The post covers first-spill capacity sampling, adaptive joinPartitionBits, adaptive joinRepartitionBits, compression selection, fallback behavior, and limitations such as row-width variance and skew.

Performance Impact

• No Impact: This change does not affect the critical path (e.g., build system, doc, error handling).

• Positive Impact: I have run benchmarks.

  Click to view Benchmark Results

  Paste your google-benchmark or TPC-H results here.
  Before: 10.5s
  After:   8.2s  (+20%)
  

• Negative Impact: Explained below (e.g., trade-off for correctness).

Release Note

Please describe the changes in this PR

Release Note:

Release Note:
- Add docs for 3 feature: row based spill, adaptive hash partition, memory management pushdown

Checklist (For Author)

• I have added/updated unit tests (ctest).
• I have verified the code with local build (Release/Debug).
• I have run clang-format / linters.
• (Optional) I have run Sanitizers (ASAN/TSAN) locally for complex C++ changes.
• No need to test or manual test.

Breaking Changes

• No

• Yes (Description: ...)

  Click to view Breaking Changes

  Breaking Changes:
  - Description of the breaking change.
  - Possible solutions or workarounds.
  - Any other relevant information.