Add Daily briefing JSON generation

docs/cli.md

@@ -1,8 +1,8 @@
 # Weatherreporter CLI
 
-`weatherreporter` currently resolves configuration, command requests, report
-definitions, and valid periods, then returns a not-implemented error for report
-generation and scheduled runs.
+`weatherreporter generate daily` currently writes a Daily briefing JSON artifact.
+Other report generation and scheduled runs still resolve configuration, report
+definitions, and valid periods, then return a not-implemented error.
 
 ## Shortest Useful Command
 
@@ -10,8 +10,8 @@ generation and scheduled runs.
 weatherreporter generate daily --date 2026-05-29 --out ./daily.md
 ```
 
-The command parses flags, loads configuration, resolves report identity and the
-valid period, and then stops before weather data fetching or report rendering.
+The command parses flags, loads configuration, fetches weather data, builds a
+Daily briefing, and writes the JSON artifact to `--out`.
 
 ## Command Overview
 
@@ -25,9 +25,9 @@ weatherreporter run morning
 weatherreporter run evening
 ```
 
-`generate` commands resolve one report request. `run` commands resolve a
-scheduled batch request. All report and batch execution currently returns
-`not implemented` after request resolution.
+`generate daily` writes a briefing JSON artifact. Other `generate` commands
+resolve one report request and stop before report generation. `run` commands
+resolve a scheduled batch request and stop before execution.
 
 ## Flags
 
@@ -35,7 +35,7 @@ scheduled batch request. All report and batch execution currently returns
 - `--config PATH`: load configuration from `PATH` instead of `/usr/local/etc/weatherreporter/config.yml`.
 - `--units VALUE`: override configured Weather API units.
 - `--tz NAME`: override configured Weather API timezone.
-- `--out PATH`: override report output path or directory for `generate` commands.
+- `--out PATH`: output path for `generate daily`; reserved for later generated report output on other `generate` commands.
 - `--date YYYY-MM-DD`: optional date for `generate daily`; defaults to the current local date in the configured timezone.
 - `--start TIME`: required start time for `generate storm`.
 - `--end TIME`: required end time for `generate storm`.