docs(agent-creator-studio): land PLAN.md + README.md for v1.3.0 Monetisation Agent S1

Adds the design doc for the AI-Native Creator Studio (Monetisation Agent S1)
— a new mode of the existing AI chat that walks creators through filling the
Creator wizard's fields in conversation, then hands off to the Creator app
for sign + mint (existing flow, unchanged).

Architectural model: "shared INTENT format, two presentations". Agent owns a
new publish_intents SQLite table (pre-encryption, user-intent fields only);
Creator app reads it via puter.args.resumeIntent=<id>, pre-fills its existing
wizard, then proceeds to its existing publish_drafts checkpoint + mint
pipeline exactly as today. No new mint pipeline, no new wallet code, no new
on-chain artifact.

Key design decisions captured:
  - 6 read-only / intent-scoped tools (analyze_file, list_my_channels,
    list_my_intents, update_intent, summarise_intent, open_creator_to_mint)
  - Chat-header mode picker as the entry trigger (default General)
  - publish_intents is a NEW table — publish_drafts is post-encryption and
    cannot host pre-encryption intent (asset_cid/metadata_cid/encrypt_hash
    are required NOT NULL — Creator app.js ~L4740)
  - Mint-handoff Option A vs Option B costed side-by-side; decision deferred
    to Sasha after review
  - NR-4 byte-for-byte regression test (agent-built intent vs manual draft
    produce identical publish_drafts row + opRawData calldata) is the
    launch gate
  - S2/S3/S4 explicitly parked (pricing-RAG, batch, voice, royalty
    monitoring, B2A negotiation)

Also rolls in the dangling ROADMAP.md housekeeping edit from the prior
session: marks the "merge lit-chipotle, tag v1.3.0" sub-bullet as superseded
(that work landed via the v1.2.7.x patch line), and annotates the Monthly
Release Cadence table as historical context.

Doc-only PR. Does not destabilise the v1.2.8.0 soak. Execution happens in
a separate ticket after Sasha sign-off on PLAN.md §15.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: SashaMIT