feat: add namespace explorer and stats

[osamashabih6960]

Summary

Adds namespace exploration and statistics support.

Changes

• Added namespace-scoped operations using namespace()
• Added namespace listing with optional search
• Added namespace statistics
• Added NamespaceStats model
• Added DynamoDB namespace discovery and storage statistics
• Added tests for namespace explorer functionality

Testing

• 73 passed
• 2 skipped

[osamashabih6960]

Implemented namespace explorer and statistics support.

Changes include:

• Namespace-scoped operations using namespace()
• Namespace listing with optional search
• Namespace statistics support
• NamespaceStats model
• DynamoDB namespace discovery and storage statistics
• Tests for namespace explorer functionality

Testing:

• 73 passed
• 2 skipped

[codeforstartups]

Thanks @osamashabih6960 — a namespace explorer is genuinely useful (issue #128/#131), and the tests pass. Two blockers before this can merge:

1. Lint fails — ruff check reports I001 (unsorted imports) in src/dynavec/client.py. Run ruff check --fix src tests.
2. client.py churn is far too large to review safely — the file goes from 574 → 1373 lines (+1059/−251), with every method rewritten. A namespace-explorer feature should be additive (new namespace_stats()/explorer methods + the models.py/stores/dynamodb.py additions), not a near-total rewrite of the core client. Please scope this down to just the new functionality and avoid reformatting/restructuring unrelated code — otherwise regressions can hide in areas the tests don't cover. If a formatter caused the churn, please revert the unrelated reformatting.

Happy to re-review quickly once it's a focused diff. The models.py + stores/dynamodb.py parts look like the right shape.

[osamashabih6960]

Hlo sir ple merged my requests

[codeforstartups]

👋 To unblock this one, two things:

1. Lint: run ruff check --fix src tests (currently fails on I001 import sorting in client.py).
2. Scope: client.py currently goes 574 → 1373 lines. Please keep the diff additive — just the new namespace-explorer methods plus the models.py / stores/dynamodb.py additions — and revert the unrelated reformatting/rewrite so it's reviewable. Then rebase on development (it now conflicts).

The models.py + stores/dynamodb.py parts look right; happy to re-review a focused diff quickly.

[codeforstartups]

👋 @osamashabih6960 — checking in on this one. Its been a couple of weeks and development has moved a lot since (query-expansion retrievers, hybrid graph search, CLI export/import, the explain path — all touching client.py), so this branch will now have significant conflicts on top of the two items still open from review:

1. Lint: ruff check --fix src tests (still failing I001 import sorting).
2. Scope: please keep the diff additive — add the namespace-explorer methods rather than restructuring client.py (the current +1312/−262 is hard to review and conflicts heavily).

Could you rebase onto latest development, run make run-ci locally until green, and push? Happy to review promptly once its rebased and lint passes. If youd rather not, no worries — just let me know and we can reassign. Thanks for the contribution!