fix: revert --since alias — Stricli only supports single-char aliases

Stricli AvailableAlias type is LowercaseLetter | UppercaseLetter,
so multi-character keys like "since" are silently ignored at runtime.
Updated agent guidance to only reference --period and -t.

Author: BYK

docs/src/content/docs/agent-guidance.md

@@ -154,11 +154,11 @@ sentry dashboard widget add <dashboard> "Top Endpoints" --display table \
 
 ### Time filtering
 
-Use `--period` (aliases: `-t`, `--since`) to filter by time window:
+Use `--period` (alias: `-t`) to filter by time window:
 
 ```bash
 sentry trace list --period 1h
-sentry span list --since 24h
+sentry span list --period 24h
 sentry span list -t 7d
 ```
 

plugins/sentry-cli/skills/sentry-cli/SKILL.md

@@ -164,11 +164,11 @@ sentry dashboard widget add <dashboard> "Top Endpoints" --display table \
 
 #### Time filtering
 
-Use `--period` (aliases: `-t`, `--since`) to filter by time window:
+Use `--period` (alias: `-t`) to filter by time window:
 
 ```bash
 sentry trace list --period 1h
-sentry span list --since 24h
+sentry span list --period 24h
 sentry span list -t 7d
 ```
 

src/lib/list-command.ts

@@ -299,7 +299,7 @@ export const LIST_PERIOD_FLAG = {
  * Exported separately from `LIST_BASE_ALIASES` because not all list commands
  * need a period flag, and some commands already use `-t` for other purposes.
  */
-export const PERIOD_ALIASES = { t: "period", since: "period" } as const;
+export const PERIOD_ALIASES = { t: "period" } as const;
 
 /**
  * Alias map shared by all list commands.