chore: bump Bamboo submodule pointer

[bigduu]

Summary

Advance the Bamboo submodule pointer through two independently reviewed, exact-head merges:

• Bamboo PR #864: restore Rust 1.98 lint compatibility and include deterministic H1 drain, account-sink restart, and PowerShell hook test repairs (#862/#865/#860/#863)
• Bamboo PR #861: centralize bounded Unix ETXTBSY spawn retries across Codex discovery, Codex exec/app-server, and Claude execution (#859)

Submodule Updates

• bamboo
  • old: 72dd35804df2b32a92490b1dfcb6e074ab56d653
  • new: 958c3af261f3622d6679d147ff67db5175348091
  • sources:
    • fix: restore Rust 1.98 lint compatibility (#862) Bamboo-agent#864
    • fix(subagent): retry transient ETXTBSY discovery (#859) Bamboo-agent#861
  • rationale: include the reviewed Rust 1.98 compatibility/stability stack and the reviewed ETXTBSY process-spawn reliability fix
  • ancestry: the old pointer is the exact merge base; the first-parent path contains only Bamboo merge commits #864 and #861, with no rewrite or skipped Bamboo history

Test Plan

• git diff-tree --no-commit-id --raw -r HEAD shows exactly one mode-160000 Bamboo gitlink update
• git ls-tree HEAD bamboo resolves to 958c3af261f3622d6679d147ff67db5175348091
• Bamboo merge ancestry resolves 72dd35804df2b32a92490b1dfcb6e074ab56d653 as the exact merge base
• Bamboo #864 and #861 required Test/E2E/Lint, CodeQL, MSRV, security, three-platform TLS, real SSH/SFTP, and full macOS/Windows/Ubuntu release matrices all passed at their exact reviewed heads
• Zenith Submodule Guard must validate this exact root head before merge

Screenshots

Not applicable; submodule pointer only.

[bigduu]

Independent exact-head agent review: APPROVE at e79155a2b123bac3c7d644806f0dbde9c56fc3f8 against main@4d043a3f8634c6d8aeb08d786013853dbde13020; no P0, P1, or P2 findings.

Verified:

• all 17 root tree entries were compared by path/mode/type/object SHA; only bamboo changes, from 72dd35804df2b32a92490b1dfcb6e074ab56d653 to 958c3af261f3622d6679d147ff67db5175348091
• all other root blobs, trees, and gitlinks are byte-identical
• the new pin equals current Bamboo dev; old pin is the exact merge base, and the first-parent path contains only Bamboo merge PR #864 then PR #861
• ## Submodule Updates, complete old/new SHAs, source links, rationale, ancestry, and Test Plan are accurate
• exact-head Submodule Guard run 32436011204 passed both pointer validation and required notes
• live PR is MERGEABLE/CLEAN with zero reviews and zero review threads

Recommendation: merge the exact reviewed head after the final live head/base/guard/thread refresh.