docs(plans): add wave-based implementation plan; decompose wave 1
- docs/plans/implementation.md: five-wave decomposition of the
architecture (foundations -> server stack -> server mappings ||
client direction -> validation & release), following the alkgit
sibling pattern (decompose-implement-gate rhythm, per-wave
decomposition records, review gates at wave boundaries)
- scope authority: v0.1.0 publishes the crate; assembly wiring stays
out; sftp decline placeholder is shipped behavior
- wave 1 decomposed into eight task files under tasks/implementation/
(manifest, error model, key sources, host-key policy, fingerprint,
config surface, test doubles, review gate) with recorded
interpretations flagged for the gate
Verification: taskgraph validate (12 tasks, no cycles); cargo test,
clippy -D warnings, fmt --check green
glm-5.3-flash
0b1bc284fa