Import type names instead of writing their paths (#355)

The style guide imports types and uses them unqualified. 222 places
wrote a path such as std::collections::HashMap or std::time::Duration
inline; each file now imports the type once, one use a module, and
names it bare. Done with a script, file by file, only where the name is
unambiguous there:
- one path for the name throughout the file, and not a name the file
  already binds otherwise (its own types, other imports, a function's
  local use);
- not a name generic enough to mislead bare (Error, Result, Value,
  Mutex, Client, Request, Response, Command, Event, Context, Map, Ok);
- only code a normal build compiles, so no import is unused outside
  tests or names a crate only tests depend on.

193 paths stay, those cases above. No behaviour change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/directory/src/config.rs

@@ -4,6 +4,8 @@
 
 use anyhow::{Context, Result, bail};
 use serde::Deserialize;
+use std::collections::HashSet;
+use std::fs::File;
 use std::path::Path;
 
 /// `directory.toml`. See docs/directory.md.
@@ -87,7 +89,7 @@ impl Config {
     /// instances' snapshots together.
     pub fn parse(text: &str) -> Result<Self> {
         let cfg: Config = toml::from_str(text)?;
-        let mut seen = std::collections::HashSet::new();
+        let mut seen = HashSet::new();
         for t in &cfg.tokens {
             if t.name.trim().is_empty() {
                 bail!("a token has an empty name");
@@ -111,7 +113,7 @@ impl Config {
     /// The tokens as the server checks them. A hash that is not 64 hex digits, or the same
     /// hash under two names, is an error: which name a request is would be ambiguous.
     pub fn tokens(&self) -> Result<Vec<Token>> {
-        let mut seen = std::collections::HashSet::new();
+        let mut seen = HashSet::new();
         self.tokens
             .iter()
             .map(|t| {
@@ -148,9 +150,7 @@ pub fn new_token() -> String {
     use std::io::Read;
     let mut bytes = [0u8; 32];
     // Falling back to the clock would make a guessable token. Better to fail.
-    std::fs::File::open("/dev/urandom")
-        .and_then(|mut f| f.read_exact(&mut bytes))
-        .expect("no source of randomness for a token");
+    File::open("/dev/urandom").and_then(|mut f| f.read_exact(&mut bytes)).expect("no source of randomness for a token");
     format!("ipxd_{}", bytes.iter().map(|b| format!("{b:02x}")).collect::<String>())
 }