fix: add .global. to connection string hostname in vector-search TS + Java

[diberry]

Closes diberry/project-dina#256

What

Adds .global.\ to the DocumentDB connection string hostname in:

• vector-search-typescript/src/utils.ts
• vector-search-java IVF.java, HNSW.java, DiskAnn.java

Why

Per Khelan Modi's guidance, all samples must use the global read-write endpoint format (<cluster>.global.mongocluster.cosmos.azure.com) to auto-follow active write region after replica promotion. Without .global., connections silently become read-only after failover.

Verification

Pattern matches vector-search-python, vector-search-go, vector-search-dotnet, and all select-algorithm samples.

[diberry]

Team Review — Round 1

Reviewer	Verdict	Notes
Statler (Devil's Advocate)	⚠️ REQUEST CHANGES	Flagged agent samples missing .global. — DISMISSED: verified all agent source files already use .global. Also noted no test evidence — N/A for sample repos.
Scooter (Quality)	✅ APPROVE	Confirmed all 4 files updated correctly; agent samples already correct; matches Python/Go reference.
Architect	⚠️ REQUEST CHANGES	Flagged README examples not using .global. — OUT OF SCOPE for this issue; separate issue to be filed.
Security	✅ APPROVE	No credential exposure, injection risk, or auth regressions. OIDC/Managed Identity model unchanged.
Algorithm	✅ APPROVE	Logic correct. .global. subdomain is DNS-level routing; no latency overhead. All format strings valid.
Integration	✅ APPROVE	SRV DNS format valid with .global., MongoDB driver handles transparently, connection params preserved.
Beauregard (PR Hygiene)	✅ APPROVE	Exactly 4 files, 4 insertions/4 deletions. In-scope only. Branch naming correct. Commit message well-formed.
Fact Checker	✅ APPROVE	.global. endpoint format verified against official Microsoft Learn DocumentDB samples. Failover behavior claim architecturally sound.

Result: 6/8 APPROVE — 2 dismissed (false positive + out of scope)

Summary

This PR correctly adds .global. to all 4 targeted connection strings in vector-search-typescript and vector-search-java samples. All source files in the repo have been verified — no other non-.global. patterns remain in any source file. Changes are minimal, surgical, and consistent with the Python/Go reference implementations.

The two REQUEST CHANGES findings were resolved:

• Statler's agent sample concern: All agent samples (�ector-search-agent-typescript, �ector-search-agent-go) already use .global. correctly.
• Architect's README concern: README documentation updates are out of scope for issue #256. A separate issue will track README alignment.

✅ Approved — ready to merge.