feat(me): add --full flag to show untruncated note content

By default, the `me` command truncates note/comment bodies to 200
characters in both the activity feed and since-last-check inbox. This
is sensible for overview displays but loses context when you need to
see the full comment text.

The new `--full` flag disables truncation, returning complete note
bodies. This affects:

- Activity feed: Note summaries now show full content
- Since-last-check inbox: Both regular comments and @mentions show
  full bodies

Implementation:
- CLI: Added `--full` boolean arg under "Output" help heading
- queries.rs: `query_activity()` and `query_since_last_check()` now
  accept a `full_body: bool` parameter that controls SQL body
  selection (`n.body` vs `SUBSTR(n.body, 1, 200)`)
- mod.rs: Wired `args.full` through to both query functions
- Tests: Added `activity_full_body_flag` and
  `since_last_check_full_body_flag` tests that verify:
  - 300-char bodies truncated to 200 without --full
  - 300-char bodies preserved in full with --full

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli/mod.rs

@@ -1123,6 +1123,10 @@ pub struct MeArgs {
     #[arg(long, help_heading = "Output", value_delimiter = ',')]
     pub fields: Option<Vec<String>>,
 
+    /// Show full note content (no truncation)
+    #[arg(long, help_heading = "Output")]
+    pub full: bool,
+
     /// Reset the since-last-check cursor (next run shows no new events)
     #[arg(long, help_heading = "Output")]
     pub reset_cursor: bool,