feat: architecture review fixes, self-update system, CI pipeline, supply chain hardening

Architecture review (all P0+P1 issues now fixed):
- Add 10s timeout to 6 bare Nostr client.connect() calls
- Pin all 12 crypto deps to exact versions from Cargo.lock
- Pin all 15 floating container image tags to exact patch versions
- Add CI pipeline (cargo fmt + clippy + tests, frontend type-check + build)

Self-update system (git.tx1138.com):
- scripts/self-update.sh: pull, build, install, restart with rollback
- systemd timer checks daily at 3 AM
- update.check RPC does git-based checks when repo is present
- update.git-apply RPC triggers self-update from UI
- Default update URL changed from GitHub to git.tx1138.com
- Git added to ISO package list for fresh installs

Documentation:
- CHANGELOG v1.3.1 with all changes
- README updated (version, update system section)
- BETA-PROGRESS session #6 logged
- architecture-review.html: 4 issues marked FIXED, 8/12 refactoring done

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/security/Cargo.toml

@@ -13,10 +13,10 @@ tracing = "0.1"
 uuid = { version = "1.0", features = ["v4"] }
 chrono = { version = "0.4", features = ["serde"] }
 serde_json = "1.0"
-aes-gcm = "0.10"
-rand = "0.8"
+aes-gcm = "0.10.3"
+rand = "0.8.5"
 hex = "0.4"
-zeroize = { version = "1", features = ["derive"] }
+zeroize = { version = "1.8.2", features = ["derive"] }
 
 [dev-dependencies]
 tempfile = "3"