feat(aura-cli): exec — the one executor verb, campaign legs + blueprint single run

The #319 retirement's constructive half, slice 1: a new top-level
`exec <target>` executes a campaign document (file, register-then-run, or
64-hex content id — byte-behaviour of the retired `campaign run`, which no
longer parses) or a fully-bound signal blueprint (synthetic single run,
record line byte-identical to `aura run`'s, root-name gate migrated).
Flag discipline is per-leg: --parallel-instruments on campaign targets,
--tap on blueprint targets (refused on campaign targets with prose).
File routing peeks the document's top-level "kind" key: is_blueprint_file
alone cannot tell two .json classes apart.

--override (the #246 residue) and the measurement leg follow in later
slices; run/sweep/walkforward/mc/generalize stay alive until the removal
slice.

refs #319

crates/aura-cli/src/research_docs.rs

@@ -65,7 +65,7 @@ impl DocIntrospectCmd {
 /// Parse `--parallel-instruments` in domain terms: clap's built-in
 /// `NonZeroUsize` parser would leak the Rust type name ("number would be
 /// zero for non-zero type") at exactly the moment a user needs guidance.
-fn parse_parallel_instruments(s: &str) -> Result<std::num::NonZeroUsize, String> {
+pub(crate) fn parse_parallel_instruments(s: &str) -> Result<std::num::NonZeroUsize, String> {
     s.parse::<usize>().ok().and_then(std::num::NonZeroUsize::new).ok_or_else(|| {
         "must be a whole number of at least 1 — it bounds how many distinct \
          instruments are resident in parallel"
@@ -411,19 +411,6 @@ pub enum CampaignSub {
     Introspect(DocIntrospectCmd),
     /// Register a valid campaign document into the store under the runs root.
     Register { file: PathBuf },
-    /// Execute a stored campaign into a realized run-set (a .json file is
-    /// register-then-run sugar; the canonical address is the content id).
-    Run {
-        target: String,
-        /// Bound on distinct instruments resident in parallel (the RAM
-        /// lever; 1 reproduces the sequential loop's footprint).
-        #[arg(
-            long,
-            default_value_t = aura_campaign::DEFAULT_PARALLEL_INSTRUMENTS,
-            value_parser = parse_parallel_instruments,
-        )]
-        parallel_instruments: std::num::NonZeroUsize,
-    },
     /// List stored campaign realizations, or dump one campaign's records
     /// (the bare store lines, not the run-emit wrapper).
     Runs { campaign: Option<String>, run: Option<usize> },
@@ -542,18 +529,7 @@ fn campaign_runs(campaign: Option<&str>, run: Option<usize>, env: &Env) -> Resul
     Ok(())
 }
 
-/// #272: `Run` threads a failed-cell count (exit 3 on completed-with-failures,
-/// via `exit_on_campaign_result`), so it is pulled out of the unified
-/// `Result<(), String>` match the other four subcommands still share.
 pub fn campaign_cmd(cmd: CampaignCmd, env: &Env) {
-    if let CampaignSub::Run { target, parallel_instruments } = &cmd.sub {
-        crate::exit_on_campaign_result(crate::campaign_run::run_campaign(
-            target,
-            env,
-            *parallel_instruments,
-        ));
-        return;
-    }
     let result = match &cmd.sub {
         CampaignSub::Validate { file } => validate_campaign_file(file, env),
         CampaignSub::Introspect(i) => {
@@ -563,7 +539,6 @@ pub fn campaign_cmd(cmd: CampaignCmd, env: &Env) {
         CampaignSub::Register { file } => register_campaign(file, env),
         CampaignSub::Runs { campaign, run } => campaign_runs(campaign.as_deref(), *run, env),
         CampaignSub::Show { id } => show_campaign(id, env),
-        CampaignSub::Run { .. } => unreachable!("handled above"),
     };
     if let Err(m) = result {
         eprintln!("aura: {m}");