docs(dsws): pool-economy implementation plan + spec lean-launch correction

Add the 10-task implementation plan (offline T1-T6, supervised GPU gates
T7-T10 each needing individual greenlight). Correct the spec (§1/§3/§6/§9):
every wave already launches lean-32 (compute grows to NFV per-rowblk, not at
init), so seeding a role is s59-assignment only — no launch-time s_alloc_vgpr,
no new OOR grow site. Drop N_POOL/SEED_* (pool size == launched mix sum, seed
== the existing wid partition); conv_apply's grow remains the only GROW in the
design. BUDGET retune knob + a compile-time WAVES*VLEAN<=BUDGET no-parking
invariant carry the grow-into-budget economy within the launched mix.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0132aDSBLwusCJ4KzHQTnvdu

Author: kmbandy