feat: proxy health & pool management (v0.2.0)

burn/timeout (dead -1 vs timed, lazy expiry), usage counters, reuse cooldown,
and live pool management (replace/add/remove) for the rotating list source.
template/static sources treat these as no-ops that log a warning.

- canonical key (host:port:user:pass, or host:port auth-less) identifies a proxy
  across every input shape (spec/Proxy/url/aiohttp/camoufox/socks5 dict); host is
  lowercased (DNS-caseless), password included, 4-part split on first 3 colons so
  colon passwords survive
- ProxiesExhaustedError when the whole pool is permanently dead
- cooldown soft (falls through to soonest-recovering, never raises); default 0 = off
- soonest-recovering fallthrough logs warning on a genuine burn, debug on cooldown
- {session} now 8-char alphanumeric (was 10-digit numeric); session_len default 8
- backward-compatible: a v0.1.0 manager (no burns, cooldown=0) is byte-for-byte
  identical — sequential round-robin, next()->Proxy, get()->aiohttp dict, never raises

Signed-off-by: disqualifier <dev@disqualifier.me>

pyproject.toml

@@ -4,8 +4,8 @@ build-backend = "hatchling.build"
 
 [project]
 name = "aioproxies"
-version = "0.1.0"
-description = "proxy parsing, formatting, and source management for aiohttp/aioweb, camoufox, and socks5"
+version = "0.2.0"
+description = "proxy parsing, formatting, health, and pool management for aiohttp/aioweb, camoufox, and socks5"
 requires-python = ">=3.10"
 dependencies = []