v0.3.5: Luxor

Release 0.3.5 Luxor (#1930)

Cuts the **v0.3.5 "Luxor"** release.

## Contents
- Bump `solang` to 0.3.5 (`Cargo.toml`), the VS Code extension to 0.3.5,
and the version references in `docs/installing.rst` /
`docs/extension.rst`.
- New `## v0.3.5 Luxor` section in `CHANGELOG.md` and
`vscode/CHANGELOG.md`.
- Refreshed `Cargo.lock`.

`solang-parser` intentionally **stays at 0.3.5**: its only change since
v0.3.4 is an inert clippy allow, 0.3.5 is already published, and
`solang` consumes the published `solang-forge-fmt 0.2.0` (which depends
on registry `solang-parser 0.3.5`) — so no parser republish is needed
and the lock keeps its validated structure.

## Depends on / includes the CI reproducibility fixes (#1929)
The release build only succeeds with the dependency fix, so this branch
is built on top of it. The first two commits are the same ones in #1929:
- `ci: commit Cargo.lock to pin ed25519-dalek and unbreak main` — a
newly-released `ed25519-dalek 3.0.0` broke `soroban-env-host`
compilation; committing `Cargo.lock` (un-ignored in `.gitignore` and
`.dockerignore`) pins it to 2.2.0 and makes CI/release builds
reproducible.
- `fix(vscode): exclude node_modules from test-suite glob` — the
extension test runner was collecting stray `*.test.js` files from
`node_modules` and aborting.

If #1929 is merged first, only the `Release 0.3.5 Luxor` commit remains
in this diff.

## Highlights since v0.3.4
- **Soroban**: `string`/`bytes`/`bytesN`, structs, (u)int256, dynamic
memory arrays, vectors-as-`VecObject`s in storage, integer width
rounding, `contract_event`-based events, and a `pause` example.
- **codegen**: large internal refactor introducing a `TargetCodegen`
trait and relocating the Solana/Polkadot/Soroban backends under
`src/codegen/targets/` (plus an `EvmTarget` scaffold).
- Toolchain moved to Rust 1.90; inkwell bumped to 0.5.0.

See `CHANGELOG.md` for the full, attributed list.

Signed-off-by: salaheldinsoliman <salaheldin_sameh@aucegypt.edu>