feat(build): add multi-platform release targets, Homebrew formula, and INSTALL.md

Taskfile:
- Add build-linux-arm64, build-darwin-amd64, build-darwin-arm64 targets
- Rename build-linux to build-linux-amd64 (keep build-linux alias)
- Rename Windows output to glint-<tag>-windows-amd64.exe for consistency
- Add build-release task that builds all five platforms in one shot

Formula/glint.rb:
- Homebrew source-build formula; depends_on "go" => :build
- tap: brew tap k3nny/glint https://github.com/k3nny/homebrew-glint
- Includes basic test block (--version + lint a trivial pipeline)

INSTALL.md:
- Pre-built binary download instructions for all five platforms
- Homebrew tap setup and formula update procedure
- go install one-liner
- Link to README integrations section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Taskfile.yml

@@ -145,30 +145,15 @@ tasks:
       - task: build
       - task: validate
 
-  build-windows:
-    desc: Build the glint binary for Windows x64 (requires a tagged commit)
+  build-linux-amd64:
+    desc: Build the glint binary for Linux x86-64 (requires a tagged commit)
+    aliases: [build-linux]
     vars:
       TAG:
         sh: git describe --tags --exact-match
     preconditions:
       - sh: git describe --tags --exact-match
-        msg: "Current commit is not tagged — Windows build requires a git tag"
-    cmds:
-      - "GOOS=windows GOARCH=amd64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}.exe ./cmd/glint/..."
-    sources:
-      - "**/*.go"
-      - go.mod
-    generates:
-      - "{{.BINARY}}-{{.TAG}}.exe"
-
-  build-linux:
-    desc: Build the glint binary for Linux x64 (requires a tagged commit)
-    vars:
-      TAG:
-        sh: git describe --tags --exact-match
-    preconditions:
-      - sh: git describe --tags --exact-match
-        msg: "Current commit is not tagged — Linux build requires a git tag"
+        msg: "Current commit is not tagged — release build requires a git tag"
     cmds:
       - "GOOS=linux GOARCH=amd64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}-linux-amd64 ./cmd/glint/..."
     sources:
@@ -177,6 +162,79 @@ tasks:
     generates:
       - "{{.BINARY}}-{{.TAG}}-linux-amd64"
 
+  build-linux-arm64:
+    desc: Build the glint binary for Linux ARM64 (requires a tagged commit)
+    vars:
+      TAG:
+        sh: git describe --tags --exact-match
+    preconditions:
+      - sh: git describe --tags --exact-match
+        msg: "Current commit is not tagged — release build requires a git tag"
+    cmds:
+      - "GOOS=linux GOARCH=arm64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}-linux-arm64 ./cmd/glint/..."
+    sources:
+      - "**/*.go"
+      - go.mod
+    generates:
+      - "{{.BINARY}}-{{.TAG}}-linux-arm64"
+
+  build-darwin-amd64:
+    desc: Build the glint binary for macOS Intel (requires a tagged commit)
+    vars:
+      TAG:
+        sh: git describe --tags --exact-match
+    preconditions:
+      - sh: git describe --tags --exact-match
+        msg: "Current commit is not tagged — release build requires a git tag"
+    cmds:
+      - "GOOS=darwin GOARCH=amd64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}-darwin-amd64 ./cmd/glint/..."
+    sources:
+      - "**/*.go"
+      - go.mod
+    generates:
+      - "{{.BINARY}}-{{.TAG}}-darwin-amd64"
+
+  build-darwin-arm64:
+    desc: Build the glint binary for macOS Apple Silicon (requires a tagged commit)
+    vars:
+      TAG:
+        sh: git describe --tags --exact-match
+    preconditions:
+      - sh: git describe --tags --exact-match
+        msg: "Current commit is not tagged — release build requires a git tag"
+    cmds:
+      - "GOOS=darwin GOARCH=arm64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}-darwin-arm64 ./cmd/glint/..."
+    sources:
+      - "**/*.go"
+      - go.mod
+    generates:
+      - "{{.BINARY}}-{{.TAG}}-darwin-arm64"
+
+  build-windows:
+    desc: Build the glint binary for Windows x86-64 (requires a tagged commit)
+    vars:
+      TAG:
+        sh: git describe --tags --exact-match
+    preconditions:
+      - sh: git describe --tags --exact-match
+        msg: "Current commit is not tagged — release build requires a git tag"
+    cmds:
+      - "GOOS=windows GOARCH=amd64 {{.GO}} build -ldflags \"-X main.version={{.TAG}}\" -o {{.BINARY}}-{{.TAG}}-windows-amd64.exe ./cmd/glint/..."
+    sources:
+      - "**/*.go"
+      - go.mod
+    generates:
+      - "{{.BINARY}}-{{.TAG}}-windows-amd64.exe"
+
+  build-release:
+    desc: Build release binaries for all supported platforms (requires a tagged commit)
+    cmds:
+      - task: build-linux-amd64
+      - task: build-linux-arm64
+      - task: build-darwin-amd64
+      - task: build-darwin-arm64
+      - task: build-windows
+
   fuzz:
     desc: "Run all fuzz targets (set FUZZ_TIME=60s to control per-target duration, default 30s)"
     cmds: