feat: Add Nix DevShell and fix all lint issues

.envrc

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+watch_dir nix
+
+use_flake

.github/workflows/flake-update.yml

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+name: "Flake.lock: update Nix dependencies"
+on:
+  workflow_dispatch: # allows manual triggering
+  schedule:
+    - cron: "0 0 * * 0" # runs weekly on Sunday at 00:00
+jobs:
+  nix-flake-update:
+    permissions:
+      contents: write
+      id-token: write
+      issues: write
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          token: ${{ secrets.GHA_PAT_TOKEN }}
+      - uses: cachix/install-nix-action@v31
+      - uses: cachix/cachix-action@v16
+        with:
+          name: kalbasit
+          authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+      - name: update flake.lock and run go mod tidy
+        id: update-flake-lock-and-go-mod-tidy
+        run: |
+          nix flake update
+          nix develop --command go mod tidy
+      - uses: EndBug/add-and-commit@v9
+        if: ${{ steps.update-flake-lock-and-go-mod-tidy.outcome == 'success' }}
+        id: commit
+        with:
+          default_author: github_actions
+          message: "chore: update flake.lock and run go mod tidy"
+          fetch: false
+          new_branch: "update-flake-lock"
+          push: --set-upstream origin "update-flake-lock" --force
+      - uses: thomaseizinger/create-pull-request@1.4.0
+        if: ${{ steps.commit.outputs.pushed == 'true' }}
+        id: create_pr
+        with:
+          github_token: ${{ secrets.GHA_PAT_TOKEN }}
+          head: "update-flake-lock"
+          base: main
+          title: "chore: update flake.lock and run go mod tidy"
+      - name: enable automerge
+        if: ${{ steps.create_pr.outputs.created }}
+        run: gh pr merge --squash --auto "${{ steps.create_pr.outputs.number }}"
+        env:
+          GH_TOKEN: "${{ secrets.GHA_PAT_TOKEN }}"

.gitignore

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+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Editor files
+/.vscode/**
+!/.vscode/settings.json
+!/.vscode/tasks.json
+!/.vscode/launch.json
+!/.vscode/extensions.json
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file used by dbmate
+.env
+
+# Go and Nix-related build result
+/ncps
+/result*
+/.direnv
+
+# Pre-commit configuration (auto-generated)
+/.pre-commit-config.yaml
+
+# Python Cache
+__pycache__/
+*.pyc
+*.pyo
+
+# Agents
+/.claude/settings.local.json

.golangci.yml

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+version: "2"
+formatters:
+  enable:
+    - gci
+    - gofumpt
+  settings:
+    gci:
+      sections:
+        - standard
+        - default
+        - alias
+        - prefix(github.com/kalbasit/sqlc-multi-db)
+        - blank
+        - dot
+      custom-order: true
+  exclusions:
+    generated: lax
+linters:
+  enable:
+    - err113
+    - errname
+    - exhaustive
+    - gochecknoglobals
+    - gochecknoinits
+    - goconst
+    - godot
+    - goheader
+    - gosec
+    - importas
+    - lll
+    - makezero
+    - misspell
+    - nakedret
+    - nestif
+    - nilerr
+    - nilnil
+    - nlreturn
+    - noctx
+    - nolintlint
+    - paralleltest
+    - prealloc
+    - predeclared
+    - revive
+    - rowserrcheck
+    - staticcheck
+    - tagliatelle
+    - testifylint
+    - testpackage
+    - unconvert
+    - unparam
+    - wastedassign
+    - whitespace
+    - wsl_v5
+    - zerologlint
+  exclusions:
+    generated: lax
+    presets:
+      - comments
+      - common-false-positives
+      - legacy
+      - std-error-handling
+    rules:
+      - path: generator/templates\.go
+        linters:
+          - lll
+  settings:
+    wsl_v5:
+      allow-first-in-block: true
+      allow-whole-block: false
+      branch-max-lines: 2

flake.nix

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+{
+  description = "TODO";
+
+  inputs = {
+
+    flake-parts = {
+      inputs.nixpkgs-lib.follows = "nixpkgs";
+      url = "github:hercules-ci/flake-parts";
+    };
+
+    git-hooks-nix = {
+      inputs.nixpkgs.follows = "nixpkgs";
+      url = "github:cachix/git-hooks.nix";
+    };
+
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+
+    treefmt-nix = {
+      inputs.nixpkgs.follows = "nixpkgs";
+      url = "github:numtide/treefmt-nix";
+    };
+
+  };
+
+  outputs =
+    inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      imports = [
+        ./nix/devshells/flake-module.nix
+        ./nix/formatter/flake-module.nix
+        ./nix/pre-commit/flake-module.nix
+      ];
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "aarch64-darwin"
+        "x86_64-darwin"
+      ];
+    };
+}

generator/constants.go

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+package generator
+
+const (
+	typeQuerier = "Querier"
+	typeAny     = "interface{}"
+	typeBool    = "bool"
+	typeString  = "string"
+	zeroNil     = "nil"
+	typeInt16   = "int16"
+	typeInt32   = "int32"
+	typeInt64   = "int64"
+	typeFloat64 = "float64"
+	typeByte    = "byte"
+
+	sqlNullString  = "sql.NullString"
+	sqlNullInt64   = "sql.NullInt64"
+	sqlNullInt32   = "sql.NullInt32"
+	sqlNullInt16   = "sql.NullInt16"
+	sqlNullBool    = "sql.NullBool"
+	sqlNullFloat64 = "sql.NullFloat64"
+	sqlNullTime    = "sql.NullTime"
+	sqlNullByte    = "sql.NullByte"
+)

generator/errors.go

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+package generator
+
+import (
+	"errors"
+	"fmt"
+)
+
+var (
+	errInvalidDictCall       = errors.New("invalid dict call")
+	errDictKeysMustBeStrings = errors.New("dict keys must be strings")
+
+	errSliceDomainStructNotSupported = errors.New(
+		"slices of domain structs are not supported as direct parameters, as they require a conversion loop" +
+			" to be generated. The auto-looping for bulk inserts handles this by operating on a struct" +
+			" parameter containing a slice",
+	)
+)
+
+func errUnsupportedSliceDomainStruct(t string) error {
+	return fmt.Errorf("unsupported parameter type: slice of domain struct %s: %w", t, errSliceDomainStructNotSupported)
+}