feat(claude-profile): add provider selection (model + endpoint + credentials)

Introduces provider files (`data/claude-profile/providers/*.yaml`) that
bundle model ID, API base URL, API key source, and extra env vars. Phase 2.5
(provider selection) added between mode selection and launch, with a default
derived from the mode's driver field so existing Anthropic usage is unchanged.

Ships 5 providers: anthropic-haiku/sonnet/opus/opus-1m and minimax-sonnet.
MiniMax token decrypted from agent-runtimes SOPS env, stored at
~/.claude-secrets/minimax-auth-token. Adding new providers = one YAML file,
no script changes.

58 dryrun tests passing (up from 37).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

data/claude-profile/presets.yaml.example

@@ -39,3 +39,10 @@ hybrid-day:
   project: cluster-bootstrap
   time_horizon: hours
   async: yes
+
+# Quick session via MiniMax (Sonnet-class, pay-per-token, no subscription)
+quick-minimax:
+  profile: oreillyit
+  mode: quick
+  provider: minimax-sonnet
+  project: small-scripts