v0.14.6 — dispatch dedup

Added

• portfolio_dispatch refuses a same-title task already open on the board (#25). The PM had no guard against re-dispatching queued work, so duplicate tasks stacked up (surfaced by Roxy dispatching several 'Assess repo' tasks). Dispatch now reads the board first and skips a normalized-title match in an open lane (done/cancelled don't count), naming the existing feature; force=true dispatches a second copy anyway, and an unreadable board never blocks. (#26)