chore(release): release v2.26.0

[tickernelz]

Summary

Release the changes accumulated since v2.25.0:

• harden project-config credential routing and keep cleanup policy global
• harden trusted Git resolution on Windows
• preserve provider extra parameters without allowing protected request fields
• preserve long-running Node cleanup requests and derive the transport timeout
• reduce DiskANN storage overhead for newly created indexes
• avoid duplicated compaction Tags footers
• show matched memory counts during search
• update web dependencies and release metadata

Verification

• bun install --frozen-lockfile (root and web)
• bun run typecheck
• bun test — 461 passed, 4 skipped, 0 failed
• bun run build
• targeted Prettier check for all changed source/package files
• git diff --check v2.25.0..HEAD
• npm pack --dry-run --json --ignore-scripts — opencode-mem-2.26.0.tgz, 241 entries; required dist and web assets present
• Standards re-review: PASS
• Spec re-review: PASS

Full repository bun run format:check still reports the unchanged pre-existing src/services/client.ts formatting issue; no release-diff file is affected.