feat: fit list tables to the terminal and write TSV when piped

Lists had no header, wrapped every row once a title was longer than
the terminal, and were space-padded when piped, so cut -f and awk -F'\t'
could not split them and empty cells collapsed.

terminal.Table now takes column specs and a Display. On a terminal it
prints an uppercase header, aligns columns two spaces apart and shrinks
flexible columns, widest first, to Streams.Width (the terminal, then
$COLUMNS, then 80), cutting by display width with "…". States use the
terminal's ANSI 16 colors, hex colors fall back to the 256-color palette
unless COLORTERM advertises 24-bit, and OSC 8 links appear only on the
first column, independently of color (TEA_HYPERLINKS=auto|always|never).
Piped tables are tab-separated without header, color or links, and times
are RFC3339 UTC instead of "about 2 hours ago".

terminal.View lays out single resources (title, badges, metadata, fields,
body, footer URL) and renders markdown bodies with glamour on a terminal
only (TEA_MARKDOWN=raw keeps them raw). Shared formatters cover relative
times, timestamps, sizes, durations and status icons.

In the app, writeTable and writeView are the new list and view writers:
a "Showing N of M …" context line, an empty-state message on stderr and
the next-page hint. writeList, writeItem and batch keep working and now
render through the new table: tab-separated when piped, truncated at the
widest column on a terminal, with headers for issue list and pr list.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/labelfile_test.go

@@ -66,5 +66,5 @@ func TestLabelImportAcceptsColorPrefixedRows(t *testing.T) {
 	require.Len(t, created, 2)
 	requirePayload(t, `{"name":"bug","color":"ee0701","description":"Something is not working"}`, strings.NewReader(created[0]))
 	requirePayload(t, `{"name":"enhancement","color":"84b6eb"}`, strings.NewReader(created[1]))
-	require.Equal(t, "1  bug\n2  enhancement\n", out.String())
+	require.Equal(t, "1\tbug\t\t\n2\tenhancement\t\t\n", out.String())
 }