chore: gitignore generated _templ.go files, track .templ sources

Generated _templ.go files are deterministic output from .templ sources,
same as output.css from input.css. Remove them from version control to
reduce diff noise and merge conflicts. Add build:templ and live:templ
tasks to the Taskfile so generation happens as part of the build.

Taskfile.yml

@@ -6,12 +6,22 @@ tasks:
     cmds:
       - go run cmd/downloader/main.go
 
+  build:templ:
+    desc: Compile .templ files to Go
+    cmds:
+      - go tool templ generate
+    sources:
+      - "**/*.templ"
+    generates:
+      - "**/*_templ.go"
+
   build:styles:
     desc: Build TailwindCSS styles
     cmds:
       - go tool gotailwind -i assets/css/input.css -o assets/css/output.css --minify
     sources:
       - "assets/css/input.css"
+      - "**/*.templ"
       - "**/*.go"
     generates:
       - "assets/css/output.css"
@@ -21,8 +31,14 @@ tasks:
     cmds:
       - go build -o bin/c4 .
     deps:
+      - build:templ
       - build:styles
 
+  live:templ:
+    desc: Watch and recompile .templ files
+    cmds:
+      - go tool templ generate -watch
+
   live:styles:
     desc: Watch and rebuild TailwindCSS styles
     cmds:
@@ -36,12 +52,13 @@ tasks:
          -build.cmd "go build -tags=dev -o tmp/bin/c4 ." \
          -build.bin "tmp/bin/c4" \
          -build.exclude_dir "data,bin,tmp,deploy" \
-         -build.include_ext "go" \
+         -build.include_ext "go,templ" \
          -misc.clean_on_exit "true"
 
   live:
     desc: Dev mode with hot-reload
     deps:
+      - live:templ
       - live:styles
       - live:server