v0.14.9 — models: one source of truth for Claude model ids, + fable (DIVE-1883)

• fix: every hardcoded Claude model id was stale, and they disagreed with each other. cmd_compose.sh mapped opus -> claude-opus-4-8 / sonnet -> claude-sonnet-4-6, agent_setup.sh defaulted the create-path pin to claude-opus-4-8, and the telegram plugin's MODEL_ALIASES mapped opus -> claude-opus-4-7 — a whole version behind the CLI. So /model opus over Telegram and 5dive compose gave you two different models, and every newly created agent was pinned to 4.8 at birth. claude-opus-5 appeared nowhere in src/.
• new src/lib/models.sh is the single source of truth. model_latest() maps opus | sonnet | fable | haiku to the current full id; resolve_model_alias() resolves an alias and passes anything else (a full id, a BYO vendor/model slug, empty) through untouched. Both CLI call sites now resolve through it. A model release is a one-line change in that file and nowhere else.
• feat: fable is selectable. The compose/create alias map only knew opus/sonnet/haiku, so fable could not be picked by alias at all. Current ids: opus claude-opus-5, sonnet claude-sonnet-5, fable claude-fable-5, haiku claude-haiku-4-5-20251001.
• feat: 5dive models [--json] prints the alias -> id map. The telegram plugin reads 5dive models --json at boot and merges the result into MODEL_ALIASES (baked defaults remain the fallback for upstream/non-5dive hosts), so the picker can no longer drift from the CLI.
• DIVE-506 behaviour is preserved deliberately. The create path still writes a FULL RESOLVED id, never a bare alias — CC >= 2.1.181 runs a startup migration (migrationVersion 13) that strips model: "opus" from a FRESH config dir, stranding a new agent on the default model. It is now resolved from the catalogue instead of a baked constant. The asymmetry with the nightly heal in 5dive-api scripts/update.sh (which writes the BARE alias to EXISTING agents, safe because their config dir is not fresh, so they float forward) is unchanged and documented in models.sh.
• out of scope, flagged: the third-party BYO/OpenRouter catalogues in header.sh (CLAUDE_PROVIDER_*_MODEL, HERMES_PROVIDER_MODEL, OPENCLAW_PROVIDER_MODEL) are vendor slugs on a different registry, not first-party ids, and were left untouched — [openrouter]="anthropic/claude-opus-4.8" looks stale next to its already-current sonnet entry, but the replacement slug needs verifying against openrouter.ai before it is changed.
• test: tests/model_aliases_unit.sh — alias resolution incl. fable, pass-through for full ids / BYO slugs / empty, every family mapped, models_json shape, a DIVE-506 guard that no resolved pin is a bare alias, a drift guard that no .sh outside models.sh re-inlines a claude-* id, and a bundle check that ./build.sh was re-run.