chore(release): DeepSQL v1.3.0 — Desktop IDE first ship

[venkateshsakamuri-lab]

Summary

Weekly product cut v1.3.0 — DeepSQL Desktop (IDE) first ship as the headline, plus Agent/Brain/Editor hardening landed on main since v1.2.0.

Release contents

• Bump backend/pom.xml → 1.3.0
• Bump desktop/package.json → 1.0.0 (installers via separate desktop-v1.0.0 tag)
• CHANGELOG.md + docs/releases/RELEASE_NOTES-v1.3.0.md
• docs/oss-ux/RELEASE.md version table + Desktop tagging notes
• Root README.md + desktop/README.md release pointers

Included since v1.2.0

PR	Topic
#73	DeepSQL Desktop — Electron thin client (TLS + SSH tunnel)
#78	Agent MCP cross-user credential leak closed
#77 / #74	Brain review approvals + schema-doc dedupe
#75	Enforceable Agent writes / non-blocking save bubbles
#76	Editor CSV export bound + concurrency/cancel audit
#71	View as Agent enforces target user policy
#70	Schema allowlist walks whole statement
#72	Brain endpoint connection authz

Not included: #80 (workspaces & custom roles) — still open; favorite-endpoint auth fix required first.

After merge

git checkout main && git pull
git tag -a v1.3.0 -m "DeepSQL v1.3.0"
git push origin v1.3.0
# optional Desktop installers:
git tag -a desktop-v1.0.0 -m "DeepSQL Desktop v1.0.0"
git push origin desktop-v1.0.0

Tag push triggers .github/workflows/release.yml for product artifacts; desktop-v* triggers .github/workflows/desktop-release.yml.