converge: phase 2 — SSE relay client for realtime pull on push

- RepoConfig gains rcGiteaRepo :: Maybe Text for relay matching
- Options gains optRelayUrl :: Maybe Text (--relay-url CLI, relay_url config)
- connectRelay connects to converge-relay SSE endpoint, parses push events,
  triggers gitPull on matching repos (by gitea_repo + branch)
- Exponential backoff reconnection (1s .. 60s) on disconnect/error
- Skips pull if repo is mid-operation (merge/rebase/etc.)
- Dependencies: http-client, http-client-tls, http-types, aeson, bytestring
- SSE parser handles event:/data: fields, blank-line delimiters, CRLF endings
- Updated SPEC.md, example config, and help text

app/Main.hs

@@ -24,6 +24,8 @@ data CliArgs = CliArgs
     -- ^ Log file path.
     , cliSync :: !Bool
     -- ^ Run a single sync cycle and exit (useful for wake-from-sleep hooks).
+    , cliRelayUrl :: !(Maybe Text)
+    -- ^ URL of a converge-relay SSE endpoint (overrides config).
     }
 
 cliParser :: Parser CliArgs
@@ -97,6 +99,13 @@ cliParser =
                 <> short 's'
                 <> help "Run a single sync cycle (commit + pull + push) and exit"
             )
+        <*> optional
+            ( strOption
+                ( long "relay-url"
+                    <> metavar "URL"
+                    <> help "URL of a converge-relay SSE endpoint for realtime push notifications"
+                )
+            )
 
 parserInfo :: ParserInfo CliArgs
 parserInfo =
@@ -114,7 +123,7 @@ main = do
     (options, configSource) <- case cliConfig cli of
         Just cfgPath -> do
             cfg <- loadConfig cfgPath
-            let opts = applyOverrides mDebounceOverride (cliLogLevel cli) (cliLogFile cli) (configToOptions cfg)
+            let opts = applyOverrides mDebounceOverride (cliLogLevel cli) (cliLogFile cli) (cliRelayUrl cli) (configToOptions cfg)
             pure (opts, Just cfgPath)
         Nothing -> do
             exists <- configFileExists
@@ -122,7 +131,7 @@ main = do
                 then do
                     cfgPath <- defaultConfigPath
                     cfg <- loadConfig cfgPath
-                    let opts = applyOverrides mDebounceOverride (cliLogLevel cli) (cliLogFile cli) (configToOptions cfg)
+                    let opts = applyOverrides mDebounceOverride (cliLogLevel cli) (cliLogFile cli) (cliRelayUrl cli) (configToOptions cfg)
                     pure (opts, Just cfgPath)
                 else
                     pure
@@ -130,6 +139,7 @@ main = do
                             mDebounceOverride
                             (cliLogLevel cli)
                             (cliLogFile cli)
+                            (cliRelayUrl cli)
                             defaultOptions
                                 { optRepos =
                                     [ defaultRepoConfig
@@ -168,13 +178,16 @@ main = do
             mapM_ (\r -> hPutStrLn stderr ("  - " <> rcPath r)) repos
             runConverge options
 
--- | Apply CLI overrides (debounce, log level, log file) to Options.
-applyOverrides :: Maybe Int -> Maybe LogLevel -> Maybe FilePath -> Options -> Options
-applyOverrides mDebounce mLogLevel mLogFile opts =
+-- | Apply CLI overrides (debounce, log level, log file, relay url) to Options.
+applyOverrides :: Maybe Int -> Maybe LogLevel -> Maybe FilePath -> Maybe Text -> Options -> Options
+applyOverrides mDebounce mLogLevel mLogFile mRelayUrl opts =
     opts
         { optDebounceMs = maybe (optDebounceMs opts) id mDebounce
         , optLogLevel = fromMaybe (optLogLevel opts) mLogLevel
         , optLogFile = case mLogFile of
             Just _ -> mLogFile -- CLI --log-file overrides config
             Nothing -> optLogFile opts
+        , optRelayUrl = case mRelayUrl of
+            Just _ -> mRelayUrl -- CLI --relay-url overrides config
+            Nothing -> optRelayUrl opts
         }