…aft spec

- Add the deprecated features registry (deprecated.mdx) and link it from the
  docs navigation
- Add a Deprecated changelog section covering SEP-2577 and the features
  grandfathered by SEP-2596, plus a governance entry for the policy itself
- Rewrite the Roots, Sampling, and Logging deprecation notices to reference
  SEP-2577, the policy's twelve-month window, and migration paths
- Retire the "soft-deprecated" wording for includeContext values in the
  sampling docs
- Document feature states in the versioning guide

…n deprecation notices

- Extract SEP-2596 policy into docs/community/feature-lifecycle.mdx and add
  to Governance nav group
- Retarget all /seps/2596-* policy links to /community/feature-lifecycle
  (versioning guide, roots/sampling/logging warnings, transports HTTP+SSE
  notice, deprecated registry, changelog)
- Replace DRAFT-2026-v1 with 2026-07-28 in deprecation prose (warning
  blocks and registry table); registry earliest-removal now reads
  'first revision released on or after 2027-07-28'
- Changelog governance entry links both the new doc and the SEP PR
- includeContext note links the policy #transition anchor

Wire-level DRAFT-2026-v1 strings (schema.ts, examples, header samples)
left for the draft->2026-07-28 directory cut.

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SEP-2577 schema annotations:
- Add @deprecated JSDoc tags to all Roots/Sampling/Logging schema items
  SEP-2577 lists (ClientCapabilities.roots/.sampling, ServerCapabilities.logging,
  Root, ListRootsRequest/Result, CreateMessageRequest/Params/Result,
  SamplingMessage/ContentBlock, ToolChoice, ToolUseContent, ToolResultContent,
  ModelPreferences, ModelHint, LoggingLevel, LoggingMessageNotification/Params).
  Types removed by SEP-2575/2322 (RootsListChangedNotification, SetLevel*,
  *ResultResponse) are not present and so not annotated.
- Align includeContext @deprecated revision with the registry (2025-11-25,
  not DRAFT-2026-v1).

SEP-1865 server-capability example:
- ext-apps defines io.modelcontextprotocol/ui as a client-only capability.
  Scope the SEP-1865 attribution in lifecycle.mdx to the client example and
  use io.modelcontextprotocol/tasks (SEP-2663) for the ServerCapabilities
  example. Rename and update the corresponding schema example file.

Policy-doc corrections:
- feature-lifecycle.mdx: fix /community/sdk-tiers anchor (#tier-relegation,
  not #tier-relegation-process); scope the 'well over twelve months'
  Transition rationale to HTTP+SSE only (includeContext was 2025-11-25).
- versioning.mdx: qualify the twelve-month floor with the expedited-removal
  exception so the summary doesn't overstate the policy guarantee.

Regenerated schema.json and schema.mdx.

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…e anchor ids

- Tag RequestMetaObject."io.modelcontextprotocol/logLevel" as @deprecated
  (SEP-2577). It is the SEP-2575 successor to the SetLevelRequest* types
  SEP-2577 lists; its value type (LoggingLevel) and the notification it
  gates (LoggingMessageNotification) were already tagged in 906af9d.
- typedoc.plugin.mjs: strip non-unique @deprecated block ids alongside the
  existing @see workaround. The 19 SEP-2577 tags otherwise produce 18
  colliding id="deprecated" anchors in the generated schema reference.
- Regenerated schema.mdx.

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…not just ids

The previous one-liner stripped the colliding ids but left dangling
href="#deprecated" / href="#see" permalink icons pointing at nothing.
These tag-block sub-headings aren't useful link targets (you'd link to the
type's own anchor), so drop both the id and the anchor icon.

Also clears 7 pre-existing dangling href="#see" permalinks in
draft/schema.mdx that the original @see workaround left behind.

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Replace the DRAFT-2026-v1 placeholder with the locked RC date across
schema/draft/ and docs/specification/draft/. The DRAFT-YYYY-vN convention
is undocumented and previously caused 2025-11-25 to ship with
LATEST_PROTOCOL_VERSION = "DRAFT-2025-v3" (corrected a week later in
35fa160). With the RC date fixed, pinning now avoids repeating that
and brings the constant in line with the @deprecated tag wording this
PR already uses.

- schema/draft/schema.ts: LATEST_PROTOCOL_VERSION = "2026-07-28"
- 19 example JSON files (_meta.protocolVersion, supported[] arrays)
- 5 spec mdx files (HTTP header samples, JSON snippets)
- schema.mdx regenerated

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