Migrate explicit struct literals to Type.{...}

[itsfuad]

Scope

Track approved explicit struct literal syntax migration to Type.{...} across PeeperLanguage/compiler, PeeperLanguage/tree-sitter-peeper, and PeeperLanguage/language-support on feature/struct-literal-dot.

Remaining review and integration

• Review and validate current uncommitted migration across all three repositories.
• Publish updated tree-sitter-peeper grammar after approval.
• Then pin the actual published grammar revision in language-support and validate extension integration; do not use a guessed revision.

Current work awaits review. No PR yet; keep this issue open. Publishing and pinning are tracked tasks, not actions authorized by this tracking update.

LSP struct literal snippet completion is explicitly deferred to #134; not part of this migration implementation.

[itsfuad]

Review completed against compiler HEAD ac49adb plus tracked/untracked migration files. Compiler committed locally as 809d462 (feat(parser): migrate named struct literals to Type.{}); no push or merge performed. Tree-sitter and Zed were already clean at existing migration commits c352e52 and 2eb83fc; their changes were inspected and validation rerun. Standards: no blocking violations found. Spec: fixed VS Code literal-head highlighting for generic qualifiers (Outer::Inner.{}), with failing-then-passing regressions. VSCodeExt has no Git metadata, so its changes remain uncommitted; no git init performed. Validation passed: touched-Go gofmt check, go test ./..., go run ./scripts/bundle.go, PEEPER_BIN=/home/itsfuad/Dev/Peeper/compiler/build/bin/peeper go test -count=1 ./x_test (6.047s), npm test -- --rebuild (13 parses), grammar generation consistency, Zed Python integration tests (2 tests/14 capture cases), cargo test --offline, cargo build --offline --target wasm32-wasip2, VS Code npm run compile and npm run test:grammar (25 cases plus multiline assertions). Excluded funding proposal, local plans, unrelated AGENTS changes/report and spec deletions, binaries/build output. extension.toml remains unchanged on remote master; installed-editor/remote-fetch integration and immutable pin remain follow-up. Keep issue open/In Progress; snippets remain deferred to #134.