chore(mesh): upgrade MeshLLM to 0.76.2 (#7559)

## Summary

Upgrade Buzz from MeshLLM `v0.76.0-rc9` to the latest stable [v0.76.2
release](https://github.com/Mesh-LLM/mesh-llm/releases/tag/v0.76.2) (via
v0.76.1).

- Update all eight Mesh git dependencies across desktop and relay smoke
examples; both lockfiles resolve all 47 Mesh packages to
`a0c1e66b0ac037dd56544b9e2d94969ea43d694f` (tag `v0.76.2`). All non-Mesh
lock records are unchanged by the 0.76.1 → 0.76.2 bump.
- Match Mesh's `ed25519-dalek = 3.0.0` and `rusqlite = 0.40`
dependencies.
- Explicitly enable rusqlite's `fallible_uint` feature, preserving
Buzz's existing `u64` SQL conversions when **mesh is disabled**.
Mesh-enabled builds previously supplied this transitively, so testing
both configurations matters.
- Temporarily pin **only** the optional `sqlx-sqlite` package to the
merged upstream compatibility fix
[transact-rs/sqlx#4402](https://github.com/transact-rs/sqlx/pull/4402),
revision `94aafe3a68884d923b0798a767c8d7f6cfda89d2`. SQLx 0.9.0 caps
`libsqlite3-sys` below 0.38, while Mesh 0.76 requires 0.38. Cargo
resolves the conflict even with SQLite disabled. The fix raises that
upper bound; remove the patch once released. Buzz's active PostgreSQL
driver stays on crates.io SQLx 0.9.0.
- Preserve the explicit Linux keyring 3 `crypto-rust` feature so Secret
Service sessions retain DH encryption independently of Mesh keyring 4.
- Preserve the dedicated examples-only `buzz-mesh-smoke` crate and
lifecycle workflow wiring, keeping Mesh/native-runtime dev dependencies
out of relay CI builds.
- v0.76.1 → v0.76.2 upstream delta: self-updater fix for composed
product-v2 bundles (Mesh-LLM/mesh-llm#1844) plus release plumbing — no
API changes affecting Buzz.
- Merged `origin/main` (`7c789dee0`) without rewriting shared PR
history.

### Validation at `ae4adba15` (local macOS ARM64, Hermit toolchain)

- **Passed:** `cargo test --locked -p buzz-mesh-smoke --all-targets`
(all six example harnesses compile; no live harness execution).
- **Passed:** desktop Tauri workspace tests, both default and
`--features mesh-llm` graphs (3,296 tests with mesh enabled, 0
failures).
- **Passed:** `just desktop-tauri-clippy` (both feature graphs, `-D
warnings`), root workspace clippy `-D warnings`, `cargo fmt --all
--check`.
- **Passed:** `--locked` metadata resolution for both workspaces;
lockfile diff audited to touch only Mesh package records.
- **Passed:** full pre-push hook suite on the final push (branch-skew,
rust-tests, desktop-tauri-checks, file-size-check) — no hooks bypassed.
- **Not run:** live Mesh inference/admission smoke or installed-app UI
exercise. CI lifecycle smoke coverage applies.

Originating Buzz conversation:
buzz://message?channel=dffbc117-845a-4c02-bc3f-eaeeefc4deaa&id=670f9c262e1ec0a4df5600b3173a0c5de2abe17e08ba9ccfdd8eff109fadf1a8

---------

Signed-off-by: Thinker <75d8a808fa21bb8d1812e080cf471db601c6e8e6a62dcd516d37531e83a7bb77@meshllm.communities.buzz.xyz>
Signed-off-by: Michael Neale <michael.neale@gmail.com>
Co-authored-by: Thinker <75d8a808fa21bb8d1812e080cf471db601c6e8e6a62dcd516d37531e83a7bb77@meshllm.communities.buzz.xyz>
Co-authored-by: Michael Neale <michael.neale@gmail.com>
Co-authored-by: Galadriel <b81c841ed20a8e17caf4e6fac2f6f3bc61d304c84b8394720f6d00f37538c47e@meshllm.communities.buzz.xyz>
Co-authored-by: Gu <gu@buzz>

.github/workflows/mesh-lifecycle.yml

@@ -12,7 +12,7 @@ on:
   push:
     branches: [main]
     paths:
-      - 'crates/buzz-relay/examples/mesh_*.rs'
+      - 'crates/buzz-mesh-smoke/**'
       - 'crates/buzz-relay/Cargo.toml'
       - 'crates/buzz-admin/**'
       - 'crates/buzz-test-client/**'
@@ -24,7 +24,7 @@ on:
       - '.github/workflows/mesh-lifecycle.yml'
   pull_request:
     paths:
-      - 'crates/buzz-relay/examples/mesh_*.rs'
+      - 'crates/buzz-mesh-smoke/**'
       - 'crates/buzz-relay/Cargo.toml'
       - 'crates/buzz-admin/**'
       - 'crates/buzz-test-client/**'